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How to find and remove lingering objects in Active Directory

Posted by Premkumar Yogeswaran on November 12, 2013

Some of the biggest annoyances for any Active Directory administrator are odd little things called lingering objects. These have existed since Windows Server 2000 and will probably never go away completely, although Microsoft has worked to give us some great tools to get rid of them and protect our domain controllers.

While there are already some good articles out there describing lingering objects, I’d like to put my own spin on the issue based on experiences I’ve had with them. I still find many Active Directory admins who either don’t understand what lingering objects are or don’t know what to do about them.

Put simply, a lingering object is any Active Directory object that has been deleted, but gets reanimated when a DC has not replicated the change during the domain’s tombstone lifetime period.

In other words, when an Active Directory object is deleted, it still exists in the AD as a tombstone. This form of the object contains only the mandatory attributes and is moved into the Deleted Objects container. The contents of the Deleted Objects container can be seen using the LDP.exe tool from the Windows Server 2003 Support Tools. Once the object is tombstoned, it will remain in this condition until the tombstone lifetime period expires (which is 60 days by default). At that point, the garbage collection process will purge it from the Active Directory.

Now suppose you have a Global Catalog server in a remote office in Brazil that has not been available on the network for the 60-day tombstone lifetime period. This could be due to maintenance, a network outage, a hardware failures, etc. that prevents the Global Catalog from replicating with the other DCs.

So let’s say you have a multiple domain forest and 100 users were deleted from the United Kingdom domain while the Brazil DC was off the network. Finally, the Brazil Global Catalog comes back online and starts replicating, but since it did not replicate the deletion of those 100 user objects which have now been purged from Active Directory, it thinks that those objects need to be replicated to its partners. So now the partners replicate the objects and those 100 accounts are alive again – sort of. Since the Brazil Global Catalog contains a read-only copy of the United Kingdom domain, it replicates read-only copies of those objects.

In this condition you will see all sorts of anomalies. You may have deleted an account called RBrown several months ago and now another person joins the company with a similar name. You try to create the RBrown account and will get an error saying it already exists. You may also see inconsistencies in the Active Directory such as two copies of an object (a lingering version and a recreated version), or you may see different objects in a user interface depending on which Global Catalog/domain controller you query. You could even get conflicting objects and find that email has failed due to inconsistencies in the Global Address List (GAL).

Preventing lingering objects

Of course, it’s most desirable to prevent lingering objects from being created in the first place. There is a registry key called StrictReplicationConsistency — which we’ll refer to asStrict Mode — that will protect a DC from lingering objects:

ValueName = Strict Replication Consistency
Data Type = Reg_DWORD
Value Data = 1 = Strict 0=Loose

If this value is set to 1, it will prevent a partner from replicating lingering objects to the DC it is defined on. Thus, if every domain controller has Strict Mode enabled, they are protected from lingering objects being propagated to them. If the value is set to 0, however, it is said to be in Loose Mode, and will allow the lingering objects to be propagated.

Now in Windows 2000 Server, the default value for StrictReplicationConsistency is loose consistency. This is important to note because if you have a domain that was upgraded to Windows Server 2003 from Windows 2000 and this key remained in the default Loose Mode, the domain will remain in loose mode. On the other hand, if you install a clean Windows Server 2003 domain, without upgrading from Windows 2000 Server, it will be in Strict Mode by default.

I’ve worked with a few organizations that suffered lingering objects because they had not taken the time to check this registry key. Again, you should always define the StrictReplicationConsistency key =1 in normal operations. It should only be set to 0 during removal of lingering objects.

Also, when Strict Mode is enabled on say DC1, and DC2 attempts to replicate an object that has been deleted on DC1, replication will be disabled between DC1 and DC2. Not just replication of the object either — all replication between the two DCs.

Determining the existence of lingering objects in the domain

Various events will either indicate the existence of Active Directory lingering objects, or will warn that they may exist. There are several events that might be logged in the Directory Service event.

Event ID 1864

This event will indicate if there are lingering objects. Note that it contains a count of how many DCs have not replicated in a day, week, month, two months, or the tombstone lifetime. The last entry is important. Unfortunately, the event will not tell us the name of the domain controller that hasn’t replicated in the tombstone lifetime.

Source NTDS Replication
Event ID 1864
This is the replication status for the following directory partition on the local domain controller.
Directory partition:

The local domain controller has not recently received replication information from a number of domain controllers. The count of domain controllers is shown, divided into the following intervals.
More than 24 hours:
More than a week:
More than one month:
More than two months:
More than a tombstone lifetime:
Tombstone lifetime (days):

Event 2042 (Error) — Source: NTDS Replication

This identifies that strict replication is enabled, the "source DC" has not replicated in tombstone lifetime days and is attempting to replicate, thus replication has been disabled from the source. The event provides the GUID of the source in the format of the CName (alias) DNS record: The friendly name of the domain controller can easily be found by looking at the Alias records in the _msdcs zone in the DNS snap-in.

Event ID 1388 (Error) – Source: NTDS Replication

Description: Another domain controller (DC) has attempted to replicate into this DC an object which is not present in the local Active Directory database. The object may have been deleted and already garbage collected (a tombstone lifetime or more has past since the object was deleted) on this DC.

Event 1988 (Error) — Source: NTDS Replication

Description: Active Directory Replication encountered the existence of objects in the following partition that have been deleted from the local domain controllers (DCs) Active Directory database. This event is being logged because the source DC contains a lingering object which does not exist on the local DCs Active Directory database.

Source DC (Transport-specific network address):

Since these are logged individually on each domain controller, you can use a tool likeMicrosoft EventComb, which is part of the Account Lockout tools download. Events 1864 and 1862 indicate the existence of lingering objects.

If you run the command Repadmin /showrepl when replication has been disabled due to strict consistency, you will see verbiage such as:

==== INBOUND NEIGHBORS ======================================

Bracknell\GSE-EXCH3 via RPC
DC object GUID: 00b71e7b-46e3-4b2e-8eef-c05f08d2ab82

******* 753 CONSECUTIVE FAILURES since 2008-12-15 11:52:10
Last error: 8614 (0x21a6):
The Active Directory cannot replicate with this server because the time since the last replication with this server has exceeded the tombstone lifetime.

From the error here, it is pretty obvious that the domain controller is being protected from an out-of-date DC. As part of regular Active Directory health maintenance, it’s a good idea to run the following command manually or by script:

Repadmin/replsum /bysrc /bydest /sort:delta

Source DC largest delta fails/total %% error
WTEC-DC2 >60 days 105 /105 100 (1722)The RPC server…
WTEC-DC1 41m:26s 0/20 0
GSE-EXCH3 08m:59s 0/6 0
WTEC-DC6 08m:34s 0/6 0

In this output, we can see how long it has been since each of the other DCs have replicated with the one on which the command has been run. Of course the red flag is WTEC-DC2 that tells us it hasn’t replicated to our target DC for more than 60 days (tombstone lifetime).

The action that should be taken in this instance is to NOT fix it. Luckily, it is not replicating or we would have the danger of lingering objects coming to our source DC if strict consistency is not enabled. The resolution for WTEC-DC1 is to remove it from the network, manually demote it, clean up the server object in Active Directory, wait for replication and re-promote it.

Removing Active Directory lingering objects

If you have found the events and errors noted above, the lingering objects need to be cleaned up. You can refer to the Microsoft articles in the box to the right for more details, but here is the quick version.

The first step is to set the StrictReplicationConsistency registry value =1 (Strict), if it isn’t already set. Be sure to check it – don’t assume you know what it is. Use the Repadmin command to set this value on all DCs:

repadmin /regkey DC_LIST +strict

Simply add the DCs to be affected in the DC_List argument.

In the Windows Server 2003 SP1 (and later) Support Tools, the Repadmin tool has a nice switch called\RemoveLingeringObjects:

/removelingeringobjects [/ADVISORY_MODE]

This is a general lingering object purge. The arguments are:

Dest_DC_List – list of DCs to operate on
Source DC GUID – the DSA GUID of a reliable DC (preferably the PDC)
NC – Naming context of the domain the lingering objects exist in.
/ADVISORY_MODE – identifies what will happen when you execute the command for real.

So a sample command would be:

C:\>Repadmin /removeLingeringObjects wtec-dc1 f5cc63b8-cdc1-4d43-8709-22b0e07b48d1 dc=wtec,dc=adapps,dc=hp,dc=com

RemoveLingeringObjects sucessfull on wtec-dc1.

After running the Repadmin command, check the event log for the events noted previously to ensure the lingering objects are removed.

Obviously for a single domain forest with a few DCs, it will be pretty easy to find the warning signs and run the Repadmin command to remove the lingering objects. In a large forest with multiple domains, however, it isn’t so easy. For instance, the lingering objects may only exist on some subset of DCs in the forest. This command would need to be run for every naming context in the forest.


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OpsMgr by Example: The Active Directory 2008 Management Pack

Posted by Premkumar Yogeswaran on November 1, 2013

This blog entry is the next in a series of Operations Manager-related items that review the steps performed to install, configure, and tune management packs in real-world environments:


1) Download the Active Directory Management Pack ( The Active Directory Management Pack Guide is included in the download and labeled “OM2007_MP_AD2008.doc.”

2) Read the Management Pack guide – cover to cover. This document spells out in detail some important pieces of information you will need to know.

3) Import the AD Management Pack (using either the Operations console or PowerShell).

4) Deploy the OpsMgr agent to all domain controllers (DCs). The agent must be deployed to all DCs. Agentless configurations will NOT work for the AD Management Pack.

5) Get a list of all domain controllers from the Operations console. In the Authoring space, navigate to Authoring -> Groups -> AD Domain Controller Group (Windows 2008 Server). Right-click on the group(s) and select View Group Members.

6) Enable Agent Proxy configuration on all Domain Controllers identified from the groups. This is in the Administration space, under Administration -> Device Management -> Agent Managed. Right-click each domain controller, select Properties, click the Security tab, and then check the box labeled “Allow this agent to act as a proxy and discover managed objects on other computers.” Perform this action for every domain controller, even if the DC is added after your initial configuration of OpsMgr.

7) Configure the Replication account in the Operations console, under Administration -> Security (full details for this are in the AD MP Guide). Do this for every domain controller, even if a DC is added after your initial OpsMgr configuration.

8) Validate the existence of the “OpsMgrLatencyMonitors” container. Within this container, create sub-folders for each DC, using the name of each domain controller. If the container does not exist, it is often due to insufficient permissions. (See information configuring the Replication account within the AD MP Guide for details.)

9) Open the Operations console. Go to the Monitoring node and navigate to Monitoring -> Microsoft Windows Active Directory -> Topology Views and validate functionality. (You may have to set the scope to the AD Domain Controllers Group to get these views to populate).

10) Check to make sure Active Directory shows up under Monitoring -> Distributed Applications as a distributed application that is in the Healthy, Warning or Critical state. If it is in the “Not Monitored” state, check for domain controllers that are not installed or are in a “gray” state.

11) Create a MicrosoftWindowsActiveDirectory_Overrides management pack to contain any overrides required for the MP (hey, if it’s not created now we’ll never remember to create it and we’ll end up using the default MP and that’s not good – see!A231E4EB0417CB76!1152.entry orSystem Center Configuration Manager 2007 Unleashed for details there).

Deploying the Active Directory 2008 Management Pack was relatively painless. After importing the management pack, there was no significant impact on processors seen on the domain controllers. The Active Directory Topology Root appeared as a distributed application and showed a health state of green. The Active Directory diagram view also worked as expected.

Tuning/Alerts to Look For

We encountered and resolved the following alerts while tuning the Active Directory management pack.

Alert: The AD Last Bind latency is above the configured threshold.

Issue: One domain controller had consistently high AD Last Bind Latency. Logon to the system showed it as extremely unresponsive.

From product knowledge, we used the suggested tasks to validate that the bind was not going slowly and no high CPU processes were identified on the system. The view available in product knowledge pointed to a large spike in the time required for the LDAP query (checking the Active Directory Last Bind counter). The spike occurred while there was a very heavy processor utilization occurring on one of the domain controllers. This monitor checks every 5 minutes. Alert auto-resolved itself after the LDAP query was responding in an acceptable timeframe.
Resolution: Attempts to debug the issue were inconclusive and extremely difficult due to the performance issue with the system. We rebooted the domain controller, it came back online, and the AD Last Bind Latency returned to normal values.

Alert:A problem has been detected with the trust relationship between two domains.

Issue: A server in a location (site 1) lost communication with domain controllers that existed in a second location (site 2). This critical alert did NOT auto-resolve. This was detected by the alert rule “A problem has been detected with the trust relationship between the two domains.” We verified that the Last Modified date occurred during the outage (add this column to the display by personalizing the view on the Active Alerts to include the field) and the Repeat Count was not incrementing.

Resolution: We used the Active Directory Domain Controller Server 2008 Computer Role Task of Enumerate Trusts to validate all trusts were working after site connectivity was re-established. We then logged into the domain controller reporting the error and used the Active Directory Domains and Trusts UI to validate each of the trusts. We closed the alert manually.

Alert:A problem with the inter-domain trusts has been detected.

Issue: A server in a location (site 1) lost communication with domain controllers that existed in a second location (site 2). This critical alert did NOT auto-resolve. This was detected by the AD Trust Monitoring monitor which runs every 5 minutes using the AD Monitor Trusts script. We verified that the Last Modified date occurred during the outage (add this column to the display by personalizing the view on the Active Alerts to include the field) and the Repeat Count was not incrementing.

Resolution: We used the Active Directory Domain Controller Server 2008 Computer Role Task of Enumerate Trusts to validate all trusts were working after site connectivity was re-established. We next logged into the domain controller reporting the error and used the Active Directory Domains and Trusts UI to validate each of the trusts. This alert should auto-resolve when the trust relationships are working, but that functionality does not appear to work. We manually closed the alert.

Alert:AD Op Master is inconsistent.

Issue: We tested using the Alert Monitor “Ad Replication Partner Op Master Consistency,” which runs every minute, to verify the incoming replication partners for the domain controller show the same operations masters. We also used the REPADMIN Replsum task in the Active Directory MP.

Resolution: The REPADMIN Replsum command validated that replication was functioning correctly (we had to override the “Support Tools Install Dir” on Windows 2008 to %windir%\system32 to make the task work correctly). The link between the domain controllers has been running close to fully saturated. The alert auto-resolved once the network utilization slowed down.

Alert:AD Client Side – Script Based Test Failed to Complete.

Issue: This alert is generated by the “AD Replication Partner Op Master Consistency” monitor. The system reporting the error was generating an error of event id 45 in the Operations Manager Log from the source of Health Service Script.

This event is occurring on an hourly basis (12:57, 1:58, and so on):

AD Replication Partner Op Master Consistency : The script ‘AD Replication Partner Op Master Consistency’ failed to execute the following LDAP query: ‘<LDAP://,DC=CONTOSO,DC=COM>;(&(objectClass=crossRefContainer)(fSMORoleOwner=*));fSMORoleOwner;Subtree’.

The error returned was ‘Table does not exist.’ (0x80040E37)

This alert is linked to “Could not determine the FSMO role holder.” alerts that are occurring.

Resolution: We believe this was related to a misconfiguration of the anti-virus settings on the domain controllers in the environment.

Alert:DC has failed to synchronize its naming context with replication partners.

Issue: A server in a location (site 1) lost communication with domain controllers that existed in a second location (site 2). The rule generating this alert is “DC has failed to synchronize naming context with its replication partner”.

Resolution: The alerts occurred when connectivity was lost between the sites. These alerts had a Repeat Count of 0. We used the REPADMIN Replsum command to validate that replication was functioning correctly (had to override the “Support Tools Install Dir” on Windows 2008 to %windir%\system32 to make the task work correctly). We closed the alerts manually.

Alert:Could not determine the FSMO role holder.

Issue: Each domain controller in the environment reported the error when trying to determine the Schema Op Master on the various domain controllers. The rule generating this was “Could not determine the FSMO role holder”.

Resolution: We used the NETDOM Query FSMO task (changing the Support Tools Install Dir to %windir%\system32) to validate the FSMO role holders on each domain controller.

Alert:DC has failed to synchronize its naming context with replication partners.

Issue: One of the domain controllers in the environment went to a grayed out status.

The server having the issues reported the “DC has failed to synchronize its naming context with replication partners” issue and “A problem has been detected with the trust relationship between two domains” and “AD Replication is occurring slowly” and “Script Based Test Failed to Complete” (for multiple AD related scripts).

Other domain controllers reported “Could not determine the FSMO role holder” and “AD Client Side – Script Based Test Failed to Complete”.

Events also occurred on the client system (21006 OpsMgr Connector, 20057 OpsMgr Connector, 21001 OpsMgr Connector).

Resolution: We installed the Telnet client feature to test connectivity to the management server. Telnet connectivity failed from this system but not from others. We then restarted the OpsMgr Health service but it had no effect on the gray status. After rebooting the system, the status went back to non-gray.

Alert: AD Client Side – Script Based Test Failed to Complete.

Issue: AD Replication Partner Op Master Consistency: The script ‘AD Replication Partner Op Master Consistency’ could not create object ‘McActiveDir.ActiveDirectory’. This is an unexpected error. The error returned was ‘ActiveX component can’t create object’ (0x1AD)

Resolution: In MOM 2005, this was resolved by changing the Action account. In OpsMgr 2007, this alert occurred in a different domain than the one with the OpsMgr RMS server. To resolve this, we created a Run As Account for the domain (DMZ) and assigned the Run As Account to the AD domain controllers in the DMZ domain.

Alert: Script Based Test Failed to Complete.

Issue: AD Lost And Found Object Count: The script ‘AD Lost And Found Object Count’ failed to create object ‘McActiveDir.ActiveDirectory’. This is an unexpected error. The error returned was ‘ActiveX component can’t create object’ (0x1AD)

Resolution: We configured the AD MP Account (Administration / Security / Run As Profiles) for each of the two servers in the domain that were reporting errors.

Alert: Script Based Test Failed to Complete.

Issue: AD Database and Log : The script ‘AD Database and Log’ failed to create object ‘McActiveDir.ActiveDirectory’. The error returned was ‘ActiveX component can’t create object’ (0x1AD).

Resolution: We configured the AD MP Account (Administration -> Security -> Run As Profiles) for each of the two servers in the domain that were reporting errors.

Alert: Performance Module could not find a performance counter.

Issue: In PerfDataSource, could not resolve counter DirectoryServices, KDC AS Requests, Module will be unloaded.

Resolution: We created a Run As Account and configured the AD MP Account (Administration -> Security -> Run As Profiles) for each of the two servers in the domain that were reporting errors.

Alert: Script Based Test Failed to Complete.

Issue: AD Database and Log : The script ‘AD Database and Log’ failed to create object ‘McActiveDir.ActiveDirectory’. The error returned was ‘ActiveX component can’t create object’ (0x1AD)

Resolution: We installed OOMADS from the OpsMgr 2007 SP 1 CD.

Alert: This domain controller has been promoted to PDC.

Issue: No issue, this was an informational message. The message was generated when the PDC emulator role was moved between domain controllers.

Resolution: No actions required, this message is provided for situations where the PDC emulator role was moved unexpectedly.

Alert: The Domain Changes report has data available.

Issue: No issue, this was an informational message. This was generated when the PDC emulator role was moved between domain controllers in the environment.

Resolution: No actions required, this message is provided for situations where the PDC emulator role was moved unexpectedly.

Alert: AD Domain Performance Health Degraded.

Issue: More than 60% of the DCs contained in this AD Domain report a Performance Health problem

Resolution: This alert indicates that there are alerts that are occurring in more than 60% of the domain controllers in a domain. This alert does not require an action for itself but does require analysis to determine what is causing the domain controllers to be in a degraded state.

Alert: AD Site Performance Health Degraded.

Issue: More than 60% of the DCs contained in this AD Site report a Performance Health problem

Resolution: This alert indicates that there are alerts that are occurring in more than 60% of the domain controllers in a site. This alert does not require an action for itself but does require analysis to determine what is causing the domain controllers to be in a degraded state.

Alert:Account Changes Report Available.

Issue: Informational alert, which can be accessed in the AD SAM Account Changes report (available on the right side under Active Directory Domain reports).

Resolution: No resolution required. We checked the AD SAM Account Changes report (available on the right-side under Active Directory Domain reports) to see the changes that were available.

During our testing, we had a period of time when we lost network connectivity to a site that had one of the domain controllers. The result was a flurry of alerts listed below:


Critical Alerts:

§ A problem with the inter-domain trusts has been detected

§ DNS 2008 Server External Addresses Resolution Alert

§ OleDB: Results Error


§ A problem has been detected with the trust relationship between two domains

§ AD Client Side – Script Based Test Failed to Complete (multiple)

§ Could not determine the FSMO role holder. (multiple)

§ DC has failed to synchronize its naming context with replication partners (multiple)

Issue: Loss of network connectivity between one site and another, both of which had domain controllers.

Resolution: Once network connectivity was re-established, we resolved all issues identified above.

UPDATE: 02/25/09

Alert: The Op Master Schema Master Last Bind latency is above the configured threshold.

Issue: A large number of alerts are generated at > 5 seconds for warning and > 15 seconds for error.

Resolution: Per the effective thresholds should be changed to warning at > 15 seconds and error at > 30 seconds. Created an override for all types of Active Directory Domain Controller Server 2008 Computer role to change Threshold Error Sec to 30 and Threshold Warning (sec) to 15 and stored it in the ActiveDirectory2008_Overrides management pack.

Alert: The Op Master Domain Naming Master Last Bind latency is above the configured threshold.

Issue: A large number of alerts are generated at > 5 seconds for warning and > 15 seconds for error.

Resolution: Per the effective thresholds should be changed to warning at > 15 seconds and error at > 30 seconds. Created an override for all types of Active Directory Domain Controller Server 2008 Computer role to change Threshold Error Sec to 30 and Threshold Warning (sec) to 15 and stored it in the ActiveDirectory2008_Overrides management pack.

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Active directory Questions

Posted by Premkumar Yogeswaran on October 22, 2013

What is Active Directory ?
Active Directory is a Meta Data. Active Directory is a data base which store a data base like your user information, computer information and also other network object info. It has capabilities to manage and administor the complite Network which connect with AD.

What is domain ?
Windows NT and Windows 2000, a domain is a set of network resources (applications, printers, and so forth) for a group of users. The user need only to log in to the domain to gain access to the resources, which may be located on a number of different servers in the network. The ‘domain’ is simply your computer address not to confused with an URL. A domain address might look something like 211.170.469.

What is domain controller ?
A Domain controller (DC) is a server that responds to security authentication requests (logging in, checking permissions, etc.) within the Windows Server domain. A domain is a concept introduced in Windows NT whereby a user may be granted access to a number of computer resources with the use of a single username and password combination.

What is LDAP ?
Lightweight Directory Access Protocol LDAP is the industry standard directory access protocol, making Active Directory widely accessible to management and query applications. Active Directory supports LDAPv3 and LDAPv2.

What is KCC ?
KCC ( knowledge consistency checker ) is used to generate replication topology for inter site replication and for intrasite replication.with in a site replication traffic is done via remote procedure calls over ip, while between site it is done through either RPC or SMTP.

Where is the AD database held? What other folders are related to AD?
The AD data base is store in c:\windows\ntds\NTDS.DIT.

What is the SYSVOL folder?
The sysVOL folder stores the server’s copy of the domain’s public files. The contents such as group policy, users etc of the sysvol folder are replicated to all domain controllers in the domain.

What are the Windows Server 2003 keyboard shortcuts ?
Winkey opens or closes the Start menu. Winkey + BREAK displays the System Properties dialog box. Winkey + TAB moves the focus to the next application in the taskbar. Winkey + SHIFT + TAB moves the focus to the previous application in the taskbar. Winkey + B moves the focus to the notification area. Winkey + D shows the desktop. Winkey + E opens Windows Explorer showing My Computer. Winkey + F opens the Search panel. Winkey + CTRL + F opens the Search panel with Search for Computers module selected. Winkey + F1 opens Help. Winkey + M minimizes all. Winkey + SHIFT+ M undoes minimization. Winkey + R opens Run dialog. Winkey + U opens the Utility Manager. Winkey + L locks the computer.

Where are the Windows NT Primary Domain Controller (PDC) and its Backup Domain Controller (BDC) in Server 2003 ?
The Active Directory replaces them. Now all domain controllers share a multimaster peer-to-peer read and write relationship that hosts copies of the Active Directory.

I am trying to create a new universal user group. Why can’t I ?
Universal groups are allowed only in native-mode Windows Server 2003 environments. Native mode requires that all domain controllers be promoted to Windows Server 2003 Active Directory.

What is LSDOU ?
It’s group policy inheritance model, where the policies are applied toLocal machines, Sites, Domains and Organizational Units.

Why doesn’t LSDOU work under Windows NT ?
If the NTConfig.pol file exist, it has the highest priority among the numerous policies.

What’s the number of permitted unsuccessful logons on Administrator account? Unlimited. Remember, though, that it’s the Administrator account, not any account that’s part of the Administrators group.

What’s the difference between guest accounts in Server 2003 and other editions?
More restrictive in Windows Server 2003.

How many passwords by default are remembered when you check "Enforce Password History Remembered"?
User’s last 6 passwords.

Can GC Server and Infrastructure place in single server If not explain why ?
No, As Infrastructure master does the same job as the GC. It does not work together.

Which is service in your windows is responsible for replication of Domain controller to another domain controller.
KCC generates the replication topology.
Use SMTP / RPC to replicate changes.

What Intrasite and Intersite Replication ?
Intrasite is the replication with in the same site & intersite the replication between sites.

What is lost & found folder in ADS ?
It’s the folder where you can find the objects missed due to conflict.
Ex: you created a user in OU which is deleted in other DC & when replication happed ADS didn’t find the OU then it will put that in Lost & Found Folder.

What is Garbage collection ?
Garbage collection is the process of the online defragmentation of active directory. It happens every 12 Hours.

What System State data contains ?
Contains Startup files,
Com + Registration Database
Memory Page file
System files
AD information
Cluster Service information

What is the difference between Windows 2000 Active Directory and Windows 2003 Active Directory? Is there any difference in 2000 Group Polices and 2003 Group Polices? What is meant by ADS and ADS services in Windows 2003?
Windows 2003 Active Directory introduced a number of new security features, as well as convenience features such as the ability to rename a domain controller and even an entire domain
Windows Server 2003 also introduced numerous changes to the default settings that can be affected by Group Policy – you can see a detailed list of each available setting and which OS is required to support it by downloading the Group Policy Settings Reference.

ADS stands for Automated Deployment Services, and is used to quickly roll out identically-configured servers in large-scale enterprise environments. You can get more information from the ADS homepage.

I want to setup a DNS server and Active Directory domain. What do I do first? If I install the DNS service first and name the zone ‘’ can I name the AD domain ‘’ too?
Not only can you have a DNS zone and an Active Directory domain with the same name, it’s actually the preferred way to go if at all possible. You can install and configure DNS before installing Active Directory, or you can allow the Active Directory Installation Wizard (dcpromo) itself install DNS on your server in the background.

How do I determine if user accounts have local administrative access?
You can use the net localgroup administrators command on each workstation (probably in a login script so that it records its information to a central file for later review). This command will enumerate the members of the Administrators group on each machine you run it on. Alternately, you can use the Restricted Groups feature of Group Policy to restrict the membership of Administrators to only those users you want to belong.

Why am I having trouble printing with XP domain users?
In most cases, the inability to print or access resources in situations like this one will boil down to an issue with name resolution, either DNS or WINS/NetBIOS. Be sure that your Windows XP clients’ wireless connections are configured with the correct DNS and WINS name servers, as well as with the appropriate NetBIOS over TCP/IP settings. Compare your wireless settings to your wired LAN settings and look for any discrepancies that may indicate where the functional difference may lie.

What is the ISTG? Who has that role by default?
Windows 2000 Domain controllers each create Active Directory Replication connection objects representing inbound replication from intra-site replication partners. For inter-site replication, one domain controller per site has the responsibility of evaluating the inter-site replication topology and creating Active Directory Replication Connection objects for appropriate bridgehead servers within its site. The domain controller in each site that owns this role is referred to as the Inter-Site Topology Generator (ISTG).

What is difference between Server 2003 vs 2008?
1. Virtualization. (Windows Server 2008 introduces Hyper-V (V for Virtualization) but only on 64bit versions. More and more companies are seeing this as a way of reducing hardware costs by running several ‘virtual’ servers on one physical machine.)
2. Server Core (provides the minimum installation required to carry out a specific server role, such as for a DHCP, DNS or print server)
3. Better security.
4. Role-based installation.
5. Read Only Domain Controllers (RODC).
6. Enhanced terminal services.
7. Network Access Protection – Microsoft’s system for ensuring that clients connecting to Server 2008 are patched, running a firewall and in compliance with corporate security policies.
8. PowerShell – Microsoft’s command line shell and scripting language has proved popular with some server administrators.
9. IIS 7 .
10. Bitlocker – System drive encryption can be a sensible security measure for servers located in remote branch offices. >br> The main difference between 2003 and 2008 is Virtualization, management. 2008 has more in-build components and updated third party drivers.
11. Windows Aero.

What are the requirements for installing AD on a new server?
1 The Domain structure.
2 The Domain Name .
3 storage location of the database and log file.
4 Location of the shared system volume folder.
5 DNS config Methode.
6 DNS configuration.

What is LDP?
LDP : Label Distribution Protocol (LDP) is often used to establish MPLS LSPs when traffic engineering is not required. It establishes LSPs that follow the existing IP routing, and is particularly well suited for establishing a full mesh of LSPs between all of the routers on the network.

What are the Groups types available in active directory ?
Security groups: Use Security groups for granting permissions to gain access to resources. Sending an e-mail message to a group sends the message to all members of the group. Therefore security groups share the capabilities of distribution groups.

Distribution groups: Distribution groups are used for sending e-main messages to groups of users. You cannot grant permissions to security groups. Even though security groups have all the capabilities of distribution groups, distribution groups still requires, because some applications can only read distribution groups.

Explain about the groups scope in AD ?
Domain Local Group: Use this scope to grant permissions to domain resources that are located in the same domain in which you created the domain local group. Domain local groups can exist in all mixed, native and interim functional level of domains and forests. Domain local group memberships are not limited as you can add members as user accounts, universal and global groups from any domain. Just to remember, nesting cannot be done in domain local group. A domain local group will not be a member of another Domain Local or any other groups in the same domain.

Global Group: Users with similar function can be grouped under global scope and can be given permission to access a resource (like a printer or shared folder and files) available in local or another domain in same forest. To say in simple words, Global groups can be use to grant permissions to gain access to resources which are located in any domain but in a single forest as their memberships are limited. User accounts and global groups can be added only from the domain in which global group is created. Nesting is possible in Global groups within other groups as you can add a global group into another global group from any domain. Finally to provide permission to domain specific resources (like printers and published folder), they can be members of a Domain Local group. Global groups exist in all mixed, native and interim functional level of domains and forests.

Universal Group Scope: These groups are precisely used for email distribution and can be granted access to resources in all trusted domain as these groups can only be used as a security principal (security group type) in a windows 2000 native or windows server 2003 domain functional level domain. Universal group memberships are not limited like global groups. All domain user accounts and groups can be a member of universal group. Universal groups can be nested under a global or Domain Local group in any domain.

What is REPLMON ?
The Microsoft definition of the Replmon tool is as follows; This GUI tool enables administrators to view the low-level status of Active Directory replication, force synchronization between domain controllers, view the topology in a graphical format, and monitor the status and performance of domain controller replication.

What is ADSIEDIT ?
ADSIEDIT :ADSIEdit is a Microsoft Management Console (MMC) snap-in that acts as a low-level editor for Active Directory. It is a Graphical User Interface (GUI) tool. Network administrators can use it for common administrative tasks such as adding, deleting, and moving objects with a directory service. The attributes for each object can be edited or deleted by using this tool. ADSIEdit uses the ADSI application programming interfaces (APIs) to access Active Directory. The following are the required files for using this tool: ADSIEDIT.DLL ADSIEDIT.

What is NETDOM ?
NETDOM is a command-line tool that allows management of Windows domains and trust relationships. It is used for batch management of trusts, joining computers to domains, verifying trusts, and secure channels.

This command-line tool assists administrators in diagnosing replication problems between Windows domain controllers.Administrators can use Repadmin to view the replication topology (sometimes referred to as RepsFrom and RepsTo) as seen from the perspective of each domain controller. In addition, Repadmin can be used to manually create the replication topology (although in normal practice this should not be necessary), to force replication events between domain controllers, and to view both the replication metadata and up-to-dateness vectors.

How to take backup of AD ?
For taking backup of active directory you have to do this : first go START -> PROGRAM ->ACCESORIES -> SYSTEM TOOLS -> BACKUP OR Open run window and ntbackup and take systemstate backup when the backup screen is flash then take the backup of SYSTEM STATE it will take the backup of all the necessary information about the syatem including AD backup , DNS ETC.

What are the DS* commands ?
The following DS commands: the DS family built in utility .
DSmod – modify Active Directory attributes.
DSrm – to delete Active Directory objects.
DSmove – to relocate objects
DSadd – create new accounts
DSquery – to find objects that match your query attributes.
DSget – list the properties of an object

What are the requirements for installing AD on a new server?
An NTFS partition with enough free space.
An Administrator’s username and password.
The correct operating system version.
A NIC Properly configured TCP/IP (IP address, subnet mask and – optional – default gateway).
A network connection (to a hub or to another computer via a crossover cable) .
An operational DNS server (which can be installed on the DC itself) .
A Domain name that you want to use .
The Windows 2000 or Windows Server 2003 CD media (or at least the i386 folder) .

Explain about Trust in AD ?
To allow users in one domain to access resources in another, Active Directory uses trusts. Trusts inside a forest are automatically created when domains are created.

The forest sets the default boundaries of trust, not the domain, and implicit, transitive trust is automatic for all domains within a forest. As well as two-way transitive trust, AD trusts can be a shortcut (joins two domains in different trees, transitive, one- or two-way), forest (transitive, one- or two-way), realm (transitive or nontransitive, one- or two-way), or external (nontransitive, one- or two-way) in order to connect to other forests or non-AD domains.

Trusts in Windows 2000 (native mode)
One-way trust – One domain allows access to users on another domain, but the other domain does not allow access to users on the first domain.
Two-way trust – Two domains allow access to users on both domains.
Trusting domain – The domain that allows access to users from a trusted domain.
Trusted domain – The domain that is trusted; whose users have access to the trusting domain.
Transitive trust – A trust that can extend beyond two domains to other trusted domains in the forest.
Intransitive trust – A one way trust that does not extend beyond two domains.
Explicit trust – A trust that an admin creates. It is not transitive and is one way only.
Cross-link trust – An explicit trust between domains in different trees or in the same tree when a descendant/ancestor (child/parent) relationship does not exist between the two domains.
Windows 2000 Server – supports the following types of trusts:
Two-way transitive trusts.
One-way intransitive trusts.
Additional trusts can be created by administrators. These trusts can be:
Windows Server 2003 offers a new trust type – the forest root trust. This type of trust can be used to connect Windows Server 2003 forests if they are operating at the 2003 forest functional level. Authentication across this type of trust is Kerberos based (as opposed to NTLM). Forest trusts are also transitive for all the domains in the forests that are trusted. Forest trusts, however, are not transitive.

Difference between LDIFDE and CSVDE?
CSVDE is a command that can be used to import and export objects to and from the AD into a CSV-formatted file. A CSV (Comma Separated Value) file is a file easily readable in Excel. I will not go to length into this powerful command, but I will show you some basic samples of how to import a large number of users into your AD. Of course, as with the DSADD command, CSVDE can do more than just import users. Consult your help file for more info.

LDIFDE is a command that can be used to import and export objects to and from the AD into a LDIF-formatted file. A LDIF (LDAP Data Interchange Format) file is a file easily readable in any text editor, however it is not readable in programs like Excel. The major difference between CSVDE and LDIFDE (besides the file format) is the fact that LDIFDE can be used to edit and delete existing AD objects (not just users), while CSVDE can only import and export objects.

What is tombstone lifetime attribute ?
The number of days before a deleted object is removed from the directory services. This assists in removing objects from replicated servers and preventing restores from reintroducing a deleted object. This value is in the Directory Service object in the configuration NIC.

What are application partitions? When do I use them ?
AN application diretcory partition is a directory partition that is replicated only to specific domain controller.Only domain controller running windows Server 2003 can host a replica of application directory partition.
Using an application directory partition provides redundany,availability or fault tolerance by replicating data to specific domain controller pr any set of domain controllers anywhere in the forest.

How do you create a new application partition ?
Use the DnsCmd command to create an application directory partition.
To do this, use the following syntax:
DnsCmd ServerName /CreateDirectoryPartition FQDN of partition

How do you view all the GCs in the forest?
C:\>repadmin /showreps domain_controller where domain_controller is the DC you want to query to determine whether it?s a GC.
The output will include the text DSA Options: IS_GC if the DC is a GC.

Can you connect Active Directory to other 3rd-party Directory Services? Name a few options.
Yes, you can use dirXML or LDAP to connect to other directories.
In Novell you can use E-directory.

What is IPSec Policy
IPSec provides secure gateway-to-gateway connections across outsourced private wide area network (WAN) or Internet-based connections using L2TP/IPSec tunnels or pure IPSec tunnel mode. IPSec Policy can be deployed via Group policy to the Windows Domain controllers 7 Servers.

What are the different types of Terminal Services ?
User Mode & Application Mode.

What is RsOP
RsOP is the resultant set of policy applied on the object (Group Policy).

What is the System Startup process ?
Windows 2K boot process on a Intel architecture.

1. Power-On Self Tests (POST) are run.

2. The boot device is found, the Master Boot Record (MBR) is loaded into memory, and its program is run.

3. The active partition is located, and the boot sector is loaded.

4. The Windows 2000 loader (NTLDR) is then loaded.

The boot sequence executes the following steps:

1. The Windows 2000 loader switches the processor to the 32-bit flat memory model.

2. The Windows 2000 loader starts a mini-file system.

3. The Windows 2000 loader reads the BOOT.INI file and displays the operating system selections (boot loader menu).

4. The Windows 2000 loader loads the operating system selected by the user. If Windows 2000 is selected, NTLDR runs NTDETECT.COM. For other operating systems, NTLDR loads BOOTSECT.DOS and gives it control.

5. NTDETECT.COM scans the hardware installed in the computer, and reports the list to NTLDR for inclusion in the Registry under the HKEY_LOCAL_MACHINE_HARDWARE hive.

6. NTLDR then loads the NTOSKRNL.EXE, and gives it the hardware information collected by NTDETECT.COM. Windows NT enters the Windows load phases.

How do you change the DS Restore admin password ?

In Windows 2000 Server, you used to have to boot the computer whose password you wanted to change in Directory Restore mode, then use either the Microsoft Management Console (MMC) Local User and Groups snap-in or the command net user administrator * to change the Administrator password.
Win2K Server Service Pack 2 (SP2) introduced the Setpwd utility, which lets you reset the Directory Service Restore Mode password without having to reboot the computer. (Microsoft refreshed Setpwd in SP4 to improve the utility?s scripting options.)

In Windows Server 2003, you use the Ntdsutil utility to modify the Directory Service Restore Mode Administrator password.

To do so, follow these steps:
1. Start Ntdsutil (click Start, Run; enter cmd.exe; then enter ntdsutil.exe).
2. Start the Directory Service Restore Mode Administrator password-reset utility by entering the argument ?set dsrm password? at the ntdsutil prompt: ntdsutil: set dsrm password.
3. Run the Reset Password command, passing the name of the server on which to change the password, or use the null argument to specify the local machine.
For example, to reset the password on server testing, enter the following argument at the Reset DSRM Administrator Password prompt: Reset DSRM Administrator Password: reset password on server testing

To reset the password on the local machine, specify null as the server name:
Reset DSRM Administrator Password: reset password on server null

4. You?ll be prompted twice to enter the new password. You?ll see the following messages:
5. Please type password for DS Restore Mode Administrator Account:
6. Please confirm new password:
Password has been set successfully.
7. Exit the password-reset utility by typing ?quit? at the following prompts:
8. Reset DSRM Administrator Password: quit
ntdsutil: quit

I am upgrading from NT to 2003. The only things that are NT are the PDC and BDCs; everything else is 2000 or 2003 member servers. My question is, when I upgrade my NT domain controllers to 2003, will I need to do anything else to my Windows 2000/2003 member servers that were in the NT domain?
Your existing member servers, regardless of operating system, will simply become member servers in your upgraded AD domain. If you will be using Organizational Units and Group Policy (and I hope you are), you’ll probably want to move them to a specific OU for administration and policy application, since they’ll be in the default "Computers" container immediately following the upgrade.

How do I use Registry keys to remove a user from a group?
In Windows Server 2003, you can use the dsmod command-line utility with the -delmbr switch to remove a group member from the command line. You should also look into the freeware utilities available from . ADFind and ADMod are indispensable tools in my arsenal when it comes to searching and modifying Active Directory.

Why are my NT4 clients failing to connect to the Windows 2000 domain?
Since NT4 relies on NetBIOS for name resolution, verify that your WINS server (you do have a WINS server running, yes?) contains the records that you expect for the 2000 domain controller, and that your clients have the correct address configured for the WINS server.

How to add your first Windows 2003 DC to an existing Windows 2000 domain ?

The first step is to install Windows 2003 on your new DC. This is a straighforward process, so we aren?t going to discuss that here.

Because significant changes have been made to the Active Directory schema in Windows 2003, we need to make our Windows 2000 Active Directory compatible with the new version. If you already have Windows 2003 DCs running with Windows 2000 DCs, then you can skip down to the part about DNS.

Before you attempt this step, you should make sure that you have service pack 4 installed on your Windows 2000 DC. Next, make sure that you are logged in as a user that is a member of the Schema Admin and Enterprise Admin groups.

Next, insert the Windows 2003 Server installation CD into the Windows 2000 Server.
Bring up a command line and change directories to the I386 directory on the installation CD. At the command prompt, type: Code :
adprep /forestprep After running this command, make sure that the updates have been replicated to all existing Windows 2000 DCs in the forest. Next, we need to run the following command: Code : adprep /domainprep

The above command must be run on the Infrastructure Master of the domain by someone who is a member of the Domain Admins group.
Once this is complete, we move back to the Windows 2003 Server. Click ?start? then ?run? – type in dcpromo and click OK. During the ensuing wizard, make sure that you select that you are adding this DC to an existing domain.
After this process is complete, the server will reboot. When it comes back online, check and make sure that the AD database has been replicated to your new server.
Next, you will want to check and make sure that DNS was installed on your new server.

If not, go to the control panel,
click on ?Add or Remove Programs?, and click the ?Add/Remove Windows Components? button.
In the Windows Components screen, click on ?Networking Services? and click the details button.

In the new window check ?Domain Name System (DNS)? and then click the OK button. Click ?Next? in the Windows Components screen.
This will install DNS and the server will reboot. After reboot, pull up the DNS Management window and make sure that your DNS settings have replicated from the Windows 2000 Server. You will need to re-enter any forwarders or other properties you had set up, but the DNS records should replicate on their own.

The next 2 items, global catalog and FSMO roles, are important if you plan on decomissioning your Windows 2000 server(s). If this is the case, you need to tansfer the global catalog from the old server to the new one.

First, let?s create a global catalog on our new server. Here are the steps:

1. On the domain controller where you want the new global catalog, start the Active Directory Sites and Services snap-in.
To start the snap-in, click ?Start?, point to ?Programs?, point to ?Administrative Tools?, and then click ?Active Directory Sites and Services?.
2. In the console tree, double-click ?Sites?, and then double-click ?sitename?.

3. Double-click ?Servers?, click your domain controller, right-click ?NTDS Settings?, and then click ?Properties?.
4. On the General tab, click to select the Global catalog check box to assign the role of global catalog to this server.
5. Restart the domain controller.

Make sure you allow sufficient time for the account and the schema information to replicate to the new global catalog server before you remove the global catalog from the original DC or take the DC offline.

After this is complete, you will want to transfer or seize the FSMO roles for your new server.
For instructions, read Using Ntdsutil.exe to transfer or seize FSMO roles to a domain controller.
After this step is complete, we can now run DCPROMO on the Windows 2000 Servers in order to demote them.

Once this is complete, copy over any files you need to your new server and you should have successfully replaced your Windows 2000 server(s) with a new Windows 2003 server.

How do you view replication properties for AD partitions and DCs?
By using replication monitor
go to start > run > type repadmin
go to start > run > type replmon

Why can’t you restore a DC that was backed up 4 months ago?
Because of the tombstone life which is set to only 60 days.

Different modes of AD restore ?
A nonauthoritative restore is the default method for restoring Active Directory. To perform a nonauthoritative restore, you must be able to start the domain controller in Directory Services Restore Mode. After you restore the domain controller from backup, replication partners use the standard replication protocols to update Active Directory and associated information on the restored domain controller.

An authoritative restore brings a domain or a container back to the state it was in at the time of backup and overwrites all changes made since the backup. If you do not want to replicate the changes that have been made subsequent to the last backup operation, you must perform an authoritative restore. In this one needs to stop the inbound replication first before performing the An authoritative restore.

How do you configure a stand-by operation master for any of the roles?
# Open Active Directory Sites and Services.
# Expand the site name in which the standby operations master is located to display the Servers folder.
# Expand the Servers folder to see a list of the servers in that site.
# Expand the name of the server that you want to be the standby operations master to display its NTDS Settings.
# Right-click NTDS Settings, click New, and then click Connection.
# In the Find Domain Controllers dialog box, select the name of the current role holder, and then click OK.
# In the New Object-Connection dialog box, enter an appropriate name for the Connection object or accept the default name, and click OK.

What’s the difference between transferring a FSMO role and seizing ?
Seizing an FSMO can be a destructive process and should only be attempted if the existing server with the FSMO is no longer available.

If you perform a seizure of the FSMO roles from a DC, you need to ensure two things:
the current holder is actually dead and offline, and that the old DC will NEVER return to the network. If you do an FSMO role Seize and then bring the previous holder back online, you’ll have a problem.

An FSMO role TRANSFER is the graceful movement of the roles from a live, working DC to another live DC During the process, the current DC holding the role(s) is updated, so it becomes aware it is no longer the role holder

I want to look at the RID allocation table for a DC. What do I do?
dcdiag /test:ridmanager /s:servername /v (servername is the name of our DC)

What is BridgeHead Server in AD ?
A bridgehead server is a domain controller in each site, which is used as a contact point to receive and replicate data between sites. For intersite replication, KCC designates one of the domain controllers as a bridgehead server. In case the server is down, KCC designates another one from the domain controller. When a bridgehead server receives replication updates from another site, it replicates the data to the other domain controllers within its site.

What is the default size of ntds.dit ?
10 MB in Server 2000 and 12 MB in Server 2003 .

Where is the AD database held and What are other folders related to AD ?
AD Database is saved in %systemroot%/ntds. You can see other files also in this folder. These are the main files controlling the AD structure.


When a change is made to the Win2K database, triggering a write operation, Win2K records the transaction in the log file (edb.log). Once written to the log file, the change is then written to the AD database. System performance determines how fast the system writes the data to the AD database from the log file. Any time the system is shut down, all transactions are saved to the database.

During the installation of AD, Windows creates two files: res1.log and res2.log. The initial size of each is 10MB. These files are used to ensure that changes can be written to disk should the system run out of free disk space. The checkpoint file (edb.chk) records transactions committed to the AD database (ntds.dit). During shutdown, a "shutdown" statement is written to the edb.chk file.

Then, during a reboot, AD determines that all transactions in the edb.log file have been committed to the AD database. If, for some reason, the edb.chk file doesn’t exist on reboot or the shutdown statement isn’t present, AD will use the edb.log file to update the AD database. The last file in our list of files to know is the AD database itself, ntds.dit. By default, the file is located in\NTDS, along with the other files we’ve discussed

What FSMO placement considerations do you know of ?
Windows 2000/2003 Active Directory domains utilize a Single Operation Master method called FSMO (Flexible Single Master Operation), as described in Understanding FSMO Roles in Active Directory.

In most cases an administrator can keep the FSMO role holders (all 5 of them) in the same spot (or actually, on the same DC) as has been configured by the Active Directory installation process.

However, there are scenarios where an administrator would want to move one or more of the FSMO roles from the default holder DC to a different DC.
Windows Server 2003 Active Directory is a bit different than the Windows 2000 version when dealing with FSMO placement.

In this article I will only deal with Windows Server 2003 Active Directory, but you should bear in mind that most considerations are also true when planning Windows 2000 AD FSMO roles

What do you do to install a new Windows 2003 R2 DC in a Windows 2003 AD?
If you’re installing Windows 2003 R2 on an existing Windows 2003 server with SP1 installed, you require only the second R2 CD-ROM.

Insert the second CD and the r2auto.exe will display the Windows 2003 R2 Continue Setup screen. If you’re installing R2 on a domain controller (DC), you must first upgrade the schema to the R2 version (this is a minor change and mostly related to the new Dfs replication engine).

To update the schema, run the Adprep utility, which you’ll find in the Components\r2\adprep folder on the second CD-ROM.
Before running this command, ensure all DCs are running Windows 2003 or Windows 2000 with SP2 (or later).

Here’s a sample execution of the Adprep /forestprep
D:\CMPNENTS\R2\ADPREP>adprep /forestprep
Before running adprep, all Windows 2000 domain controllers in the forest should be upgraded to Windows 2000 Service Pack 1 (SP1) with QFE 265089, or to Windows 2000 SP2 (or later).

QFE 265089 (included in Windows 2000 SP2 and later) is required to prevent potential domain controller corruption.
[User Action] If ALL your existing Windows 2000 domain controllers meet this requirement, type C and then press ENTER to continue. Otherwise, type any other key and press ENT ER to quit.
C Opened Connection to SAV

DALDC01 SSPI Bind succeeded Current Schema Version is 30 Upgrading schema to version 31 Connecting to "SAVDALDC01" Logging in as current user using SSPI Importing directory from file "C:\WINDOWS\system32\sch31.ldf" Loading entries… 139 entries modified successfully.

The command has completed successfully Adprep successfully updated the forest-wide information.
After running Adprep, install R2 by performing these steps:

1. Click the "Continue Windows Server 2003 R2 Setup" link, as the figureshows.
2. At the "Welcome to the Windows Server 2003 R2 Setup Wizard" screen, click Next.
3. You’ll be prompted to enter an R2 CD key (this is different from your existing Windows 2003 keys) if the underlying OS wasn’t installed from R2 media (e.g., a regular Windows 2003 SP1 installation).
Enter the R2 key and click Next. Note: The license key entered for R2 must match the underlying OS type, which means if you installed Windows 2003 using a volume-license version key, then you can’t use a retail or Microsoft Developer Network (MSDN) R2 key.
4. You’ll see the setup summary screen which confirms the actions to be performed (e.g., Copy files). Click Next.
5. After the installation is complete, you’ll see a confirmation dialog box. Click Finish

What is OU ?
Organization Unit is a container object in which you can keep objects such as user accounts, groups, computer, printer . applications and other (OU).
In organization unit you can assign specific permission to the user’s. organization unit can also be used to create departmental limitation.

Name some OU design considerations ?
OU design requires balancing requirements for delegating administrative rights – independent of Group Policy needs – and the need to scope the application of Group Policy.

The following OU design recommendations address delegation and scope issues:
Applying Group Policy An OU is the lowest-level Active Directory container to which you can assign Group Policy settings.
Delegating administrative authority
usually don’t go more than 3 OU levels

What is sites ? What are they used for ?
One or more well-connected (highly reliable and fast) TCP/IP subnets.
A site allows administrators to configure Active Directory access and replication topology to take advantage of the physical network.

A Site object in Active Directory represents a physical geographic location that hosts networks. Sites contain objects called Subnets.

Sites can be used to Assign Group Policy Objects, facilitate the discovery of resources, manage active directory replication, and manage network link traffic.
Sites can be linked to other Sites. Site-linked objects may be assigned a cost value that represents the speed, reliability, availability, or other real property of a physical resource. Site Links may also be assigned a schedule.

Trying to look at the Schema, how can I do that ?
register schmmgmt.dll using this command
c:\windows\system32>regsvr32 schmmgmt.dll
Open mmc –> add snapin –> add Active directory schema
name it as schema.msc
Open administrative tool –> schema.msc

What is the port no of Kerbrose ?

What is the port no of Global catalog ?

What is the port no of LDAP ?

Explain Active Directory Schema ?
Windows 2000 and Windows Server 2003 Active Directory uses a database set of rules called "Schema". The Schema is defines as the formal definition of all object classes, and the attributes that make up those object classes, that can be stored in the directory. As mentioned earlier, the Active Directory database includes a default Schema, which defines many object classes, such as users, groups, computers, domains, organizational units, and so on.

These objects are also known as "Classes". The Active Directory Schema can be dynamically extensible, meaning that you can modify the schema by defining new object types and their attributes and by defining new attributes for existing objects. You can do this either with the Schema Manager snap-in tool included with Windows 2000/2003 Server, or programmatically.

How can you forcibly remove AD from a server, and what do you do later? ? Can I get user passwords from the AD database?
Dcpromo /forceremoval , an administrator can forcibly remove Active Directory and roll back the system without having to contact or replicate any locally held changes to another DC in the forest. Reboot the server then After you use the dcpromo /forceremoval command, all the remaining metadata for the demoted DC is not deleted on the surviving domain controllers, and therefore you must manually remove it by using the NTDSUTIL command.

In the event that the NTDS Settings object is not removed correctly you can use the Ntdsutil.exe utility to manually remove the NTDS Settings object. You will need the following tool: Ntdsutil.exe, Active Directory Sites and Services, Active Directory Users and Computers

What are the FSMO roles? Who has them by default? What happens when each one fails?
Flexible Single Master Operation (FSMO) role. Currently there are five FSMO roles:
Schema master
Domain naming master
RID master
PDC emulator
Infrastructure master

What is domain tree ?
Domain Trees: A domain tree comprises several domains that share a common schema and configuration, forming a contiguous namespace. Domains in a tree are also linked together by trust relationships. Active Directory is a set of one or more trees.
Trees can be viewed two ways. One view is the trust relationships between domains. The other view is the namespace of the domain tree.

What is forests ?
A collection of one or more domain trees with a common schema and implicit trust relationships between them. This arrangement would be used if you have multiple root DNS addresses.

How to Select the Appropriate Restore Method ?
You select the appropriate restore method by considering:
Circumstances and characteristics of the failure. The two major categories of failure, From an Active Directory perspective, are Active Directory data corruption and hardware failure.

Active Directory data corruption occurs when the directory contains corrupt data that has been replicated to all domain controllers or when a large portion of the Active Directory hierarchy has been changed accidentally (such as deletion of an OU) and this change has replicated to other domain controllers.

Where are the Windows NT Primary Domain Controller (PDC) and its Backup Domain Controller (BDC) in Server 2003?
The Active Directory replaces them. Now all domain controllers share a multimaster peer-to-peer read and write relationship that hosts copies of the Active Directory.

What is Global Catalog?
The Global Catalog authenticates network user logons and fields inquiries about objects across a forest or tree. Every domain has at least one GC that is hosted on a domain controller. In Windows 2000, there was typically one GC on every site in order to prevent user logon failures across the network.

How long does it take for security changes to be replicated among the domain controllers?
Security-related modifications are replicated within a site immediately. These changes include account and individual user lockout policies, changes to password policies, changes to computer account passwords, and modifications to the Local Security Authority (LSA).

When should you create a forest?
Organizations that operate on radically different bases may require separate trees with distinct namespaces. Unique trade or brand names often give rise to separate DNS identities. Organizations merge or are acquired and naming continuity is desired. Organizations form partnerships and joint ventures. While access to common resources is desired, a separately defined tree can enforce more direct administrative and security restrictions.

Describe the process of working with an external domain name ?
If it is not possible for you to configure your internal domain as a subdomain of your external domain, use a stand-alone internal domain. This way, your internal and external domain names are unrelated. For example, an organization that uses the domain name for their external namespace uses the name corp.internal for their internal namespace.

The advantage to this approach is that it provides you with a unique internal domain name. The disadvantage is that this configuration requires you to manage two separate namespaces. Also, using a stand-alone internal domain that is unrelated to your external domain might create confusion for users because the namespaces do not reflect a relationship between resources within and outside of your network.

In addition, you might have to register two DNS names with an Internet name authority if you want to make the internal domain publicly accessible.

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Active Directory 2008 features

Posted by Premkumar Yogeswaran on October 22, 2013

Whats new in windows 2008 Active Directory

As an Active Directory administrator very curies about the windows 2008 features compare to the earlier version like windows 2003, Windows 2008 comes with the whole bunch of features, and am going to discuss specific about the features of Active Directory server roles in Windows 2008


Now you can know the previous and present values for the changed attributes of the active directory object using the new auditing feature in windows 2008, as per the windows 2003 auditing you will only know the present values of the changed attribute

This is very useful features in windows 2008 since you can revert back the changes using the previous value of the attribute

Fine-Grained Passwords

By default in windows 2003 all the user account in the domain should use the same password policy configured in domain level, thats why we called domain is a security boundary, if you require a different password policy then you have to create new domain

In windows 2008 password policy can be configured for specific group of peoples with in the domain

Read-Only Domain Controller

Everyone know about the BDC (backup domain controller) and it’s a same as the BDC but it only take the advantages from the BDC and it’s specifically designed for the today’s requirements like branch office setup and to managing the branch office

We all know how difficult to design and manage the domain controller from the branch office, some time it lead to the lingering object, but using the Read-Only Domain Controller
In the branch office where the physical security of the domain controller is in question, or domain controllers that host additional roles, requiring other users to log on and maintain the server

In any Active Directory environment if one Domain Controller not replicated with the partner Domain Controller more then one month, then it’s a very critical issue you have to rectify the replication problem as soon as possible or the Domain Controller needs to be decommissioned with in the tombstone lifetime, since its read-only domain controller no worries about the tombstone time.

Restartable Active Directory Domain Services

Hey good new, now no need to restart the domain controller for every time for the active directory maintenance.

In windows 2008 active directory is a services, you can stop or restart the services for maintenance without restarting the domain controller and restarting it in Directory Services Restore Mode is not required for most maintenance functions, however still some maintenance function require Directory Services Restore Mode

Database Mounting Tool

Active Directory Database mounting tool in Windows Server 2008 to create and view snapshots of data that is stored in Active Directory Domain Services, and no need to restart the domain controller. A snapshot is a shadow copy created by the Volume Shadow Copy Service, at different times so that you can better choose which data to restore after object deletion. This reduces the administrator time and no need to restore multiple backups to compare the Active Directory data.

Active Directory Database mounting tool can be called Snapshot Viewer, Snapshot Browser, and Active Directory data mining tool.

Active Directory Recycle Bin

You can restore the accidentally deleted Active Directory object, without Active Directory authoritative restore, this can be used for single object restore like a accidental deletion of user or OU and you can reduce the domain controller downtime

Active Directory module for Windows PowerShell

PowerShell available on windows 2003 itself, however it’s not fully supported for Active Directory, you can’t manage the Active Directive using the PowerShell in windows 2003

In windows 2008 Windows PowerShell provides command-line scripting for administrative, configuration, and diagnostic tasks

You can manage the Active Directory with Exchange Server, Group Policy, and other services and it’s very easy to use like a windows commands, you can easily pipe cmdlets to build complex operations

Active Directory Administrative Center

It’s new tool in windows 2008 R2 to manage active directory, we already have active directory users and computer to manage the active directory, using this new tool you can manage active directory in a new way

As an administrator you perform most of the task commonly that is daily, some how it’s hard to open an active directory user and computer and find the object and do the task, in this new tool Active Directory Administrative Center it’s very easy to do a common task like password reset and search the Active Directory object and others

Active Directory Best Practices Analyzer

This can be helped to identify and implement the best practices in the configuration of your active directory environment, this will scan your network and find the best practice violations,
Then you can correct that, to get the best out of Active Directory services in windows 2008.

Active Directory Web Services

Active Directory Web Services is give you the Web service interface to Active Directory domains and AD LDS instances (Active Directory Lightweight Directory Services)

Active Directory Database Mounting Tool uses the Active Directory Web Services as a front end, like that Windows PowerShell and Active Directory Administrative Center is used the Active Directory Web Services to access the directory service instances.

Offline domain join

Offline domain join makes to join a member server to the domain even the domain controller not reachable from the member server

And this can be very useful for bulk deployment, when the system starts, it will automatically joined to the domain, this will reduce the administrative effort

Managed Service Accounts

Normally applications and services uses the Local Service and Network Service and Local System accounts, it’s easy to configure and shared among multiple applications and services and cannot be managed on a domain level

You can use the domain account for the application (services), this can isolate the privileges for the application, but it’s very hard to manage these domain accounts like password management

We have two new types of accounts, Managed service accounts and virtual accounts in windows 2008, now you can easily manage the service principal names (SPNs), it will provide Automatic password management

Active Directory Management Pack

You can monitor the Active Directory service on windows 2008 using the Active Directory Management Pack (MOM, SCOM)

Designed specifically to monitor the performance and availability of Active Directory Domain Services (AD DS), also monitors the overall health of AD DS and alerts you to critical performance issues.

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SYSVOL Folder Structure

Posted by Premkumar Yogeswaran on October 22, 2013

About each folder under the SYSVOL share in Domain Controller

SYSVOL folder used to store a copy of the domain’s public files like system policies, Group Policy settings and logon/logoff scripts, which are replicated to all other domain controllers in the Active Directory domain through File Replication Services (FRS), You can find many folders inside the SYSVOL share, I would like to explore and explain each folder by how it’s used in the process of SYSVOL replication.

SYSVOL Folder Structure
| |____Policies
| |____Scripts
| |____ DO_NOT_REMOVE_NtFrs_PreInstall_Directory
| |____ NtFrs_PreExisting___See EventLog
| |____Policies
| |____Scripts
| |____Domain
| |____Enterprise
|____Staging Areas
| |____Enterprise (junction> = Sysvol\Staging\Enterprise)
| |____Your Domain Name (junction> = Sysvol\Staging\Domain)
| |____Enterprise (junction> = Sysvol\Enterprise)
| |____Your Domain Name (junction> = Sysvol\Domain)

Before I discuss about the SYSVOL folder structure, we should know about the junction points,

Junction point: is a physical location on a hard disk that points to data that is located elsewhere on the hard disk or on another storage device. Junction points look like folders and behave like folders but they are not folders. A junction point contains a link to another folder. When a program opens it, the junction point automatically redirects the program to the folder to which the junction point is linked

If you open a \\%systemroot%\SYSVOL\sysvol, it actually opens the content in %systemroot%\SYSVOL\domain, you can also see this in command prompt, go to SYSVOL folder in command prompt and type DIR you can notice some of folder are shown as all are junction points

%systemroot%\SYSVOL\staging areas\domainnam pointing to %systemroot%\SYSVOL\staging\domain

%systemroot%\SYSVOL\sysvol pointing to %systemroot%\SYSVOL\domain

Staging Folder
When ever you change the GPO settings the corresponding policy folder in SYSVOL get updated and this change needs to be replicated to other replication members (Domain controller) how it’s happens? Staging folder acts like a queue for changed files and folders to be replicated to downstream partners.

FRS creates a file in staging folder by using APIs (backup application programming interfaces) based on the change and replicates to the downstream partners, downstream partners use restore APIs to reconstruct the staging files in the preinstall folder, full file get copied from staging folder to preinstall folder.

Preinstall folder
Preinstall folder is nothing but the DO_NOT_REMOVE_NtFrs_PreInstall_Directory. Folder located under the replica root (Domain folder). Files and folders are replicated from the upstream partner staging folder. After the file or folder is completely replicated, it is renamed to its target location in the replica tree. So that partially constructed files are not visible in the replica tree

Pre-existing folder
The pre-existing folder, named NtFrs_PreExisting___See EventLog, is an optional folder that is located under the replica root (Domain folder). It may not be available by default like others folders, If pre-existing folder is present on a replica member then mostly one of the below reasons.

• Active Directory Restore:
• SYSVOL Non-authoritative restore (also called D2):
• Server was pre-staged before it was added to the replica set

Mostly FRS moves existing data in the replica tree to the pre-existing folder and then receives the updated replica tree from one of the upstream partners and deletes the files inside the pre-existing folder after the successful completion of replication.

Policies Folder
Policy folder contains the list of folders for each policy, if you create a new Group Policy it will create a Group policy templates folder on SYSVOL share under policy, it will contain the group policy setting related to that policy, GPT folder name would be Globally Unique Identifier (GUID) of the GPO that you created.

Scripts Folder
Script Folder contains all the logon/logoff scripts which is used by the various policies

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Sysvol Replication change in Windows 2008

Posted by Premkumar Yogeswaran on October 22, 2013

Group Policy replication change

Before I start the SYSVOL replication changes in windows server 2008, I would like to explain how the GPO has been replicated in windows server 2003 and earlier versions

Understanding SYSVOL/GPO replication

Group policy template (GPT) and group policy container (GPC) are two types of Group policy settings, Its stored in two different locations and uses different replication technology to replicate the changes, however both should be available up-to-date on domain controller to function properly

Group policy templates are stored in SYSVOL, it’s a folder structure in SYSVOL share on a domain controller, if you create a new Group Policy it will create a Group policy templates folder on SYSVOL share for the new policy that contain the group policy setting related to this policy, GPT folder name would be Globally Unique Identifier (GUID) of the GPO that you created, you can view all the GPT folders from the below Path (it’s a default GPT path)


Group Policy template (GPT) is replicated by SYSVOL through FRS, FRS uses state-based replication. As soon as there is a change to any file under the Sysvol folder structure, replication is triggered and entire file get replicated

Group policy containers are stored in Active Directory, mostly all the GPO setting are stored in GPT (Group policy templates), GPC only have the reference information of the corresponding GPO, like GPT path, GUID of the GPO, version information, WMI filter information, and a list of components that have settings in the GPO, you can view the GPC from Active Directory Users and Computers (ADUC)


Group policy container (GPC) is replicated through Active Directory replication

Note: By default the Group Policy Management Editor console (GPME) uses the PDC Emulator so that all administrators can work on the same domain controller, if you want a different Domain controller you can change through Group Policy Management console (GPMC)

File Replication Services (FRS)

I will try to explain step by step, let say you modify the Policy A from Server001 and how this change get replicated to Server002 (Server002 is a downstream replication partner for server001)

Once you modify the Policy A from server001, the corresponding GPT folder on SYSVOL gets updated on the server001 (also updates the Group policy containers in Active Directory on server001)

NTFS will change the USN journal according to the file and folder change.

FRS monitors the USN journal for changes on the SYSVOL folder

FRS updates the inbound log on server001, FRS not only updates the local changes on inbound log, also updates the inbound log for the changes from entire upstream replication partner (all inbound partners)

FRS creates a file in staging folder on server001 by using APIs (backup application programming interfaces) based on the change.

This change has been updated on outbound log on server001 by FRS. And also send change notification to entire downstream replication partner about the change (all outbound partners)

Server002 get the change notification from Server001 and store the change order in inbound log, Server002 copies the staging file from Server001 to the staging folder on Server002. Server002 then update outbound log so other outbound partners can pick up the change

Using Restore APIs, Server002 reconstructs the file and folder in the preinstall folder, and then FRS renames the file or folder into the replica tree

In FRS replication process the entire changed file and folder get replicate to source to destination server

What is NTFS USN journal?

Logs all the changes to an NTFS volume, including file creations, deletions, and changes, Separate log on each NTFS volume and it has a size limit (Windows server 2003 SP2 & Windows server 2008 is 128 MB) if require you can increase the size up to 2 TB, however MS Recommends increasing by 128 MB for every 100,000 files/folders

What happens when the NTFS USN change journal fills up?

If the USN journal log fills up then NTFS will be overwrite the old entry’s, that’s why in some scenarios before the change get updated, NTFS delete the entries in USN journal log, it’s called journal_wrap

USN journal wrap Error

An error that occurs when large numbers of files change so quickly that the USN journal must remove the oldest changes (before FRS has a chance to detect the changes) to stay within the specified size limit, to resolve this issue you have to perform a non-authoritative restore also called D2

Morphed folder

Replication conflict will occur if identically named directories are created in different servers, to resolve this conflict FRS create a folder and this folder called morphed folder

Let’s say two identical directories are created in different replication members, FRS identifies the conflict during replication, and the receiving member protects the original copy of the folder and renames (morphs) the later inbound copy of the folder. The morphed folder names have a suffix of “_NTFRS_xxxxxxxx,” where “xxxxxxxx” represents eight random hexadecimal digits.

Version vector join (vvjoin)

Till now we are discussing about the SYSVOL replication, how the SYSVOL replication works for the newly added replication partner, newly added replication member doesn’t have any updates, and it should build the folder structure from the beginning, this process is called vvjoin, in which a downstream partner joins with an upstream partner for the first time.

Vvjoin is a CPU-intensive operation that can affect the performance of the server and increase the replication traffic

Distributed File System (DFS)

Now we are coming to the point, how the SYSVOL replicating using DFS and how it’s been improved to provide better replication performance, to use this feature you should have Windows Server 2008 domain functional level that means all the domain controller has to be Windows Server 2008

SYSVOL replication using DFS is called DFS-Replicated SYSVOL (DFSR)

DFSR is a multimaster replication engine and changes that occur on one of the replication member are then replicated to all of the other servers in the replication group

DFSR also monitors the NTFS for the update sequence number (USN) journal to detects changes on the volume, and then DFSR replicate the changes only after the file closed

And before sending or receiving a file, DFSR uses a staging folder to stage the file

If any changes in SYSVOL share, FRS replicate the entire file unlike the DFSR, DFSR replicates only the changes blocks and not the entire file, sounds like a attribute level Active Directory replication, it compare the source and destination file using remote differential compression (RDC), it reduce the SYSVOL replication traffic

Other Difference between DFRS and FRS

DFSR and Journal Wraps, DFSR also monitors the NTFS change journal, but DFSR always heals itself hence no Journal Wrap error

Morphed files and folders automatically taken care of

FRS silently fails if the volume SYSVOL resides on < 1GB of free space

Copies the changes on files and folder not entire files and folder

Uses Version Vector tables to confirm the changes, also to resolve the conflicts

Support read-only replication on a particular members in which users cannot add or change files

You can also make the changes to the SYSVOL folder of an RODC

DFSR does not require the version vector join (vvjoin) operation

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Force sysvol replication

Posted by Premkumar Yogeswaran on October 22, 2013

How do I force the Sysvol replication in an active directory

You can restart the FRS service to force the FRS replication

To restart the FRS service, launch services.msc from the Run option on the Start Menu
And restart the FRS service and you will get the Event ID 13516 on FRS event log this will ensure the FRS status is fine

Forcing Sysvol replication through NTFRSUTL

If you want to force sysvol replication between two domain controllers in an active directory then use the below procedure

NTFRSUTL FORCEREPL Command-Line Option to Force Replication

You can use the new ntfrsutl forcerepl command to enforce replication regardless of the predefined replication schedule. This is only implemented for the domain controller Sysvol replica set.

ntfrsutl forcerepl [Computer] /r [SetName] /p [DnsName]

This command forces FRS to start a replication cycle. You must specify the Computer, SetName and DnsName.

Note In this command, the following placeholders are used:
[Computer] = Connect with the NtFrs service on this machine.
[SetName] = The name of the replica set.
[DnsName] = The DNS name of the inbound partner to force replication from.

For example:

ntfrsutl.exe forcerepl DestinationDC /r "Domain System Volume (SYSVOL share)" /p

The quotation marks in this example are required when you use the /r option. If the quotation marks are not present, the command will not work.

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Active Directory Replication

Posted by Premkumar Yogeswaran on October 22, 2013

Force Active Directory replication

AD replication is scheduled however some time we require to synchronize manually

There is many ways to do this we will see one by one

Force active directory replication through the Microsoft Management Console (MMC) or Forcing replication through Active Directory Sites and Services snap-in

Go to Start –> Programs –> Administrative Tools –> and open the “Active Directory Sites and Services” MMC.
Expand the “Sites” container in the left pane by clicking the plus (+) to the left of it.
Expand the container that represents the name of the site containing the server that needs to be synchronized.
Expand the “Servers” container and then expand the target server to display the NTDS settings object.
Click the “NTDS Settings” option. In the right pane should now be a list of the target server’s replication partners.
Right click a connection object in the right pane and click “Replicate Now

Force active directory replication through Replmon Tool

Go to Start –> Run –> type replmon –>and this will open a Replmon console
Click on > edit and select –> Add monitored server
Select –>Add the server explicitly by name –>Next
Enter the server name that needs to be synchronized > Finish
Expand the Partition that needs to be synchronized (Exg: Domain partition)
Select the connection object needs to be synchronized
Right click a connection object and click “Synchronize with this replication partner”
Wait for the replication
You will get the status message once the replication get completed
If any error while the time of replication then you will get the meaningful error message

Force active directory replication through Repadmin command

Open the Command prompt CMD
repadmin /replicate destination_dsa source_dsa Naming Context

repadmin /replicate dc=Domain,dc=com

Destination server Name:
Source server Name:
Naming Context : dc=Domain,dc=com (Domain partition)

Additional switches

This parameter is used to override the Disable Replication option on a directory server. Do not use this parameter unless you are certain that replication has been disabled, and that you want to override this setting.

Specifies that the operation will be asynchronous. This means that repadmin starts the replication event, but it does not expect an immediate response from the destination directory server. Use this parameter when there are slow links between directory servers.

Forces a full replication of all objects from the destination directory server.

A given destination can have multiple sources for the same naming context. Directs the destination to sync with all sources instead of just one. This parameter cannot be used with source_dsa.

Force the active directory replication with the entire replication partner

In some scenario you want to force active directory replication with the entire replication partner, let say you have a 10 connection objects corresponding to each of its replication partners and you want to force the replication to all the connection objects on, you can use the blow command.

repadmin /replicate destination_dsa Naming Context /allsources

repadmin /replicate dc=test,dc=com /allsources

Destination server Name:
Naming Context: dc=test,dc=com (Domain partition)

I would strongly recommend to use the Replmon tool or repadmin command,to force active directory replication since you will get the meaningful error message and the status message once the replication get completed

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Interesting findings on SETSPN -x -f

Posted by Premkumar Yogeswaran on October 17, 2013

Kerberos is becoming increasingly mandatory for really cool features such as Protocol Transition. Moreover, as you might be painfully aware, managing Service Principal Names (SPN’s) for the use of Kerberos by applications can be daunting at times.

In this blog, we will not be going into the gory details of SPNs and how applications are using them. In fact, I’m assuming you already have some basic knowledge about SPN’s and how they are used.

Instead, we’re going to talk about an interesting behavior that can occur when an administrator is doing their due diligence managing SPN’s. This behavior can arise when you are checking the status of the account the SPN is planned for, or when you are checking to see if the SPN that must be registered is already registered in the domain or forest.

As we all know, the KDC’s cannot issue tickets for a particular service if there are duplicate SPN’s, and authentication does not work if the SPN is on the wrong account.

Experienced administrators learn to use the SETSPN utility to validate SPNs when authentication problems occur. In the Windows Server 2008 version of SETSPN, we provide several options useful to identifying duplicate SPNs:

– If you want to look for a duplicate of a particular SPN: SETSPN /q <SPN>

– If you want to search for any duplicate in the domain: SETSPN /x

You can also use the “/f” option to extend the duplicate search to the whole Forest. Many Active Directory Admins use this as a proactive check of the forest for duplicate SPNs.

So far, so good…

The Problem

Sometimes, you’ll get an error running SETSPN -x -f:

c:>SETSPN -X -F -P
Checking forest DC=contoso,DC=com
Operation will be performed forestwide, it might take a while.
Ldap Error(0x55 — Timeout): ldap_get_next_page_s

“-P” just tells the tool not to clutter the output with progress indications, but you can see from that error message that we are not talking only about Kerberos anymore. There is a new problem.

What are we seeing in the diagnostic data?

In a network trace of the above you will see a query against the GC (port 3268) with no base DN and the filter “(servicePrincipalName=*)”. SETSPN uses paged queries with a page size of 100 objects. In a large Active Directory environment this yields quite a number of pages.

If you look closely at network capture data, you’ll often find that Domain Controller response times slowly increase towards the end of the query. If the command completes, you’ll sometimes see that the delay is longest on the last page returned. For example, when we reviewed data for a recent customer case, we noted:

”Customer also noticed that it usually hangs on record 84.”

Troubleshooting LDAP performance and building custom queries calls for the use of the STATS Control. Here is how you use it in LDP.exe:

Once connected to port 3268 and logged on as an admin, you can build the query in the same manner as SETSPN does.

1. Launch LDP as an administrator.

2. Open the Search Window using BrowseSearch or Ctrl-S.

3. Enter the empty base DN and the filter, specify “Subtree” as the scope. The list of attributes does not matter here.

4. Go to Options:

5. Specify an “Extended” query as we want to use controls. Note I have specified a page size of 100 elements, but that is not important, as we will see later. Let’s move on to “Controls”:

5. From the List of Controls select “Search Stats“. When you select it, it automatically checks it in.

6. Now “OK” your way out of the “Controls” and “Options” dialogs.

7. Hit “Run” on the “Search” dialog.

You should get a large list of results, but also the STATS a bit like this one:

Call Time: 62198 (ms)

Entries Returned: 8508

Entries Visited: 43076

Used Filter: (servicePrincipalName=*)

Used Indices: idx_servicePrincipalName:13561:N

Pages Referenced : 801521

Pages Read From Disk : 259

Pages Pre-read From Disk : 1578

Pages Dirtied : 0

Pages Re-Dirtied : 0

Log Records Generated : 0

Log Record Bytes Generated: 0

What are these stats telling us?

We have a total of 8508 objects in the “Entries Returned” result set, but we have visited 43076 objects. That sounds odd, because we used an Index “idx_servicePrincipalName”. This does not really look as if the query is using the index.

So what is happening here?

At this point, we experience the special behavior of multi-valued non-linked attributes and how they are represented in the index. To illustrate this, let me explain a few data points:

1. A typical workstation or member server has these SPNs:









2. When you look at the result set from running setspn, you notice that you’re not getting all of the SPNs you’d expect:

dn:CN=HQSCCM2K3TEST,OU=SCCM,OU=Test Infrastructure,OU=Domain Management,DC=contoso,DC=com

servicePrincipalName: WSMAN/sccm2k3test

servicePrincipalName: WSMAN/

If you look at it closely, you notice all the SPN’s start with characters very much at the end of the alphabet, which also happens to be the end of the index. These entries do not have a prefix like “HOST”.

So how does this happen?

In the resultant set of LDAP queries, an object may only appear once, but it is possible for an object to be in the index multiple times, because of the way the index is built. Each time the object is found in the index, the LDAP Server has to check the other values of the indexed attribute of the object to see whether it also matches the filter and thus was already added to the result set. The LDAP server is doing its diligence to avoid returning duplicates.

For example, the first hit in the index for the above workstation example is “HOST/HERBERTM5“.

The second hit “HOST/“ kicks off the algorithm.

The object is read already and the IO and CPU hit has happened.

Now the query keeps walking the index, and once it arrives at the prefix “WSMAN”, the rate of objects it needs to skip approaches 100%. Therefore, it looks at many objects and little additional objects in the result set.

On the last page of the query, things get even worse. There is an almost 100% rate of duplicates, so the clock of 60 seconds SETSPN allows for the query is ticking, and there are only 8 objects to be found. If the Domain Controller has a slow CPU or the objects need to be read from the disk because of memory pressure, the SETSPN query will probably not finish within a minute for a large forest. This results in the error Ldap Error(0x55 — Timeout): ldap_get_next_page_s. The larger the index (meaning, the more computers and users you have in your forest), the greater the likelihood that this can occur.

If you run the query with LDIFDE, LDP or ADFIND you will have a better chance the query will be successful. This is because by default these tools do not specify a time-out and thus use the values of the Domain Controller LDAP Policy. The Domain Controller LDAP policy is 120 seconds (by default) instead of 60 seconds.

The problem with the results generated by these tools is that you have to correlate the results from the different outputs yourself – the tools won’t do it for you.

So what can you do about it?

Typically you’ll have to do further troubleshooting, but here are some common causes/resolutions that I’ve seen:

  1. If a domain controller is short on memory and encounters many cache misses and thus substantial IO. You can diagnose this using the NTDS performance counters in Performance Monitor. You can add memory to reduce the IO rate and speed things up.
  2. If you are not experiencing memory pressure, the limiting factor could be the “Single-Thread-Performance” of the server. This is important as every LDAP query gets a worker thread and runs no faster than one logical CPU core can manage. If you have a low number of logical cores in a system with a high amount of CPU activity, this can cause the threads to delay long enough for us to see an nconsistent query return. In this situation your best bet is to look for ways to reduce overall processor load on the domain controller – for example, moving other services off of the machine.
  3. There is an update for Windows Server 2012 which helps to avoid the problem:

2799960 Time-out error when you run SETSPN.exe in Windows 8 or Windows Server 2012

The last customer I helped had a combination of issues 1 and 2 and once he chose a beefier DC with more current hardware, the command always succeeded. Another customer had a much bigger environment and ended up using the update I listed above to overcome the issue.

I hope you have enjoyed this journey explaining what is happening on such a SETSPN query.

Refer Below Link:

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Good Links for Event ID search

Posted by Premkumar Yogeswaran on October 16, 2013

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