Re-installing a Domain Controller
This article is written to give readers a heads up about some issues involved when re-installing a Domain controller. This article is particulary about re-installing a Windows 2000 domain controller and issues that may occur if the re-installation is not done properly.
This article is to be used at the readers own risk and the author nor this project can be held liable for any damage related to this article or your use of information contained here. You could seriously damage Active Directory if you perform tasks related to this subject improperly. This article will outline the issue and point to resources for further information.
If a Windows 2000 domain controller crashes and cannot be gracefully removed from the domain, there are some Active Directory maintenance tasks which should be performed prior to the re-installation of that domain controller or the installation of a new domain controller.
Background
Active Directory is the control mechanism for your Windows domain which allows users to be created or removed and controls access to various objects in the network including servers, workstations, and files. You should be aware that Active Directory treats everything as an object and assigns a unique identifing number to each object including your domain controller servers. When your domain controller is re-created, it will not have the same identifying number. Therefore it is important to use the correct process when dealing with these important objects. There are two cases which may occur when a domain controller must be re-installed:
Crashed Domain Controller which must be replaced or re-installed
If your domain controller crashes and must be re-installed you should clean up Active Directory before installing a new domain controller or re-installing your domain controller. See Microsoft's Knowledge Base Article Q216498 at http://support.microsoft.com/default.aspx?scid=kb;en-us;216498
This procedure describes how to use the NTDS Utility program to clean up active directory. This procedure must be done precisely to avoid damaging Active Directory. If you have not followed the procedures properly, or have installed a new domain controller before cleaning up Active Directory and/or have noticed some unusual effects which may be caused by Active Directory corruption, you should call Microsoft technical support IMMEDIATELY. I recommend that you DO NOT attempt to clean up the corruption yourself.
Windows Server 2003 Service Pack 1 (SP1) or later service packs – Enhanced version of Ntdsutil.exe
The version of Ntdsutil.exe that is included with Service Pack 1 or later service packs for Windows Server 2003 has been enhanced to make the metadata cleanup process complete. The Ntdsutil.exe version that is included with SP1 or later service packs does the following when metadata cleanup is run:- Removes the NTDSA or NTDS Setting subject.
- Removes inbound AD connection objects that existing destination DCs use to replicate from the source DC being deleted .
- Removes the computer account .
- Removes FRS member object.
- Removes FRS subscriber objects.
- Tries to seize flexible single operations master roles (also known as flexible single master operations or FSMO) held by the DC that are being removed .
Procedure 1: Windows Server 2003 SP1 or later service packs only
- Click Start, point to Programs, point to Accessories, and then click Command Prompt.
- At the command prompt, type ntdsutil, and then press ENTER.
- Type metadata cleanup, and then press ENTER. Based on the options given, the administrator can perform the removal, but additional configuration parameters must be specified before the removal can occur.
- Type connections and press ENTER. This menu is used to connect to the specific server where the changes occur. If the currently logged on user does not have administrative permissions, different credentials can be supplied by specifying the credentials to use before making the connection. To do this, type set credsDomainNameUserNamePassword, and then press ENTER. For a null password, typenull for the password parameter.
- Type connect to server servername, and then press ENTER. You should receive confirmation that the connection is successfully established. If an error occurs, verify that the domain controller being used in the connection is available and the credentials you supplied have administrative permissions on the server.
Note If you try to connect to the same server that you want to delete, when you try to delete the server that step 15 refers to, you may receive the following error message:Error 2094. The DSA Object cannot be deleted0x2094 - Type quit, and then press ENTER. The Metadata Cleanup menu appears.
- Type select operation target and press ENTER.
- Type list domains and press ENTER. A list of domains in the forest is displayed, each with an associated number.
- Type select domain number and press ENTER, where number is the number associated with the domain the server you are removing is a member of. The domain you select is used to determine whether the server being removed is the last domain controller of that domain.
- Type list sites and press ENTER. A list of sites, each with an associated number, appears.
- Type select site number and press ENTER, where number is the number associated with the site the server you are removing is a member of. You should receive a confirmation listing the site and domain you chose.
- Type list servers in site and press ENTER. A list of servers in the site, each with an associated number, is displayed.
- Type select server number, where number is the number associated with the server you want to remove. You receive a confirmation listing the selected server, its Domain Name System (DNS) host name, and the location of the server's computer account you want to remove.
- Type quit and press ENTER. The Metadata Cleanup menu appears.
- Type remove selected server and press ENTER. You should receive confirmation that the removal completed successfully. If you receive the following error message, the NTDS Settings object may already be removed from Active Directory as the result of another administrator removing the NTDS Settings object or replication of the successful removal of the object after running the DCPROMO utility.Error 8419 (0x20E3)
The DSA object could not be found
Note You may also see this error when you try to bind to the domain controller that will be removed. Ntdsutil has to bind to a domain controller other than the one that will be removed with metadata cleanup. - Type quit, and then press ENTER at each menu quit the Ntdsutil utility. You should receive confirmation that the connection disconnected successfully.
- Remove the cname record in the _msdcs.root domain of forest zone in DNS. Assuming that DC will be reinstalled and re-promoted, a new NTDS Settings object is created with a new GUID and a matching cname record in DNS. You do not want the DCs that exist to use the old cname record.
As best practice, you should delete the host name and other DNS records. If the lease time that remains on Dynamic Host Configuration Protocol (DHCP) address assigned to offline server is exceeded then another client can obtain the IP address of the problem DC. - In the DNS console, use the DNS MMC to delete the A record in DNS. The A record is also known as the Host record. To delete the A record, right-click the A record, and then click Delete. Also, delete the cname record in the _msdcs container. To do this, expand the _msdcs container, right-click cname, and then click Delete.
Important If this is a DNS server, remove the reference to this DC under the Name Servers tab. To do this, in the DNS console, click the domain name under Forward Lookup Zones, and then remove this server from the Name Servers tab.
Note If you have reverse lookup zones, also remove the server from these zones. - If the deleted computer is the last domain controller in a child domain, and the child domain was also deleted, use ADSIEdit to delete the trustDomain object for the child. To do this, follow these steps:
- Click Start, click Run, type adsiedit.msc, and then click OK
- Expand the Domain NC container.
- Expand DC=Your Domain, DC=COM, PRI, LOCAL, NET.
- Expand CN=System.
- Right-click the Trust Domain object, and then click Delete.
- Use Active Directory Sites and Services to remove the domain controller. To do this, follow these steps:
- Start Active Directory Sites and Services.
- Expand Sites.
- Expand the server's site. The default site is Default-First-Site-Name.
- Expand Server.
- Right-click the domain controller, and then click Delete.
- When you use DFS Replication in Windows Server 2008 and in later versions, the current version of Ntdsutil.exe does not clean up the DFS Replication object. In this case, you can use Adsiedit.msc to correct the DFS Replication objects for Active Directory Domain Services (AD DS) manually. To do this, follow these steps:
- Logon a domain controller as a domain administrator in the affected domain.
- Start Adsiedit.msc.
- Connect to the default naming context.
- Locate the following DFS Replication topology container:CN=Topology,CN=Domain System Volume,CN=DFSR-Globalsettings,CN=System,DC=Your Domain,DC=Domain Suffix
- Delete the msDFSR-Member CN object that has the old computer name.
Procedure 2: Windows 2000 (All versions) Windows Server 2003 RTM
- Click Start, point to Programs, point to Accessories, and then click Command Prompt.
- At the command prompt, type ntdsutil, and then press ENTER.
- Type metadata cleanup, and then press ENTER. Based on the options given, the administrator can perform the removal, but additional configuration parameters must be specified before the removal can occur.
- Type connections and press ENTER. This menu is used to connect to the specific server where the changes occur. If the currently logged on user does not have administrative permissions, different credentials can be supplied by specifying the credentials to use before you make the connection. To do this, type set credsDomainNameUserNamePassword, and then press ENTER. For a null password, typenull for the password parameter.
- Type connect to server servername, and then press ENTER. You should receive confirmation that the connection is successfully established. If an error occurs, verify that the domain controller being used in the connection is available and the credentials you supplied have administrative permissions on the server.
Note If you try to connect to the same server that you want to delete, when you try to delete the server that step 15 refers to, you may receive the following error message:Error 2094. The DSA Object cannot be deleted0x2094 - Type quit, and then press ENTER. The Metadata Cleanup menu appears.
- Type select operation target and press ENTER.
- Type list domains and press ENTER. A list of domains in the forest is displayed, each with an associated number.
- Type select domain number and press ENTER, where number is the number associated with the domain the server you are removing is a member of. The domain you select is used to determine whether the server being removed is the last domain controller of that domain.
- Type list sites and press ENTER. A list of sites, each with an associated number, is displayed.
- Type select site number and press ENTER, where number is the number associated with the site the server you are removing is a member of. You should receive a confirmation listing the site and domain you chose.
- Type list servers in site and press ENTER. A list of servers in the site, each with an associated number, is displayed.
- Type select server number, where number is the number associated with the server you want to remove. You receive a confirmation listing the selected server, its Domain Name System (DNS) host name, and the location of the server's computer account you want to remove.
- Type quit and press ENTER. The Metadata Cleanup menu appears.
- Type remove selected server and press ENTER. You should receive confirmation that the removal completed successfully. If you receive the following error message:the NTDS Settings object may already be removed from Active Directory as the result of another administrator removing the NTDS Settings object, or replication of the successful removal of the object after you run the Dcpromo utility.Error 8419 (0x20E3)
The DSA object could not be found
Note You may also see this error when you try to bind to the domain controller that will be removed. Ntdsutil has to bind to a domain controller other than the one that will be removed with metadata cleanup. - Type quit at each menu to quit the Ntdsutil utility. You should receive confirmation that the connection disconnected successfully.
- Remove the cname record in the _msdcs.root domain of forest zone in DNS. Assuming that DC will be reinstalled and re-promoted, a new NTDS Settings object is created by using a new GUID and a matching cname record in DNS. You do not want the DC's that exist to use the old cname record.
As best practice you should delete the hostname and other DNS records. If the lease time that remains on Dynamic Host Configuration Protocol (DHCP) address assigned to offline server is exceeded then another client can obtain the IP address of the problem DC.
Note You do not need to manually remove the FRS member object in Windows Server 2003 RTM because the Ntdsutil.exe utility has already removed the FRS member object when you run the utility. Additionaly, the metadata of the computer account cannot be removed if the computer account of the DC contains another leaf object. For example, Remote Installation Services (RIS) might be installed on the DC.
The Adsiedit utility is included with the Windows Support Tools feature in both Windows 2000 Server and Windows Server 2003. To install the Windows Support Tools, following these steps:
- Windows 2000 Server: On the Windows 2000 Server CD, open the Support\Tools folder, double-click Setup.exe, and then follow the instructions that appear on the screen.
- Windows Server 2003: On the Windows Server 2003 CD, open the Support\Tools folder, double-click Suptools.msi, click Install, and then follow the steps in the Windows Support Tools Setup Wizard to complete the installation.
- Use ADSIEdit to delete the computer account. To do this, follow these steps:
- Click Start, click Run, type adsiedit.msc in the Open box, and then click OK.
- Expand the Domain NC container.
- Expand DC=Your Domain Name, DC=COM, PRI, LOCAL, NET.
- Expand OU=Domain Controllers.
- Right-click CN=domain controller name, and then click Delete.
Note The FRS subscriber object is deleted when the computer object is deleted because it is a child of the computer account. - Use ADSIEdit to delete the FRS member object. To do this, follow these steps:
- Click Start, click Run, type adsiedit.msc in the Open box, and then click OK
- Expand the Domain NC container.
- Expand DC=Your Domain, DC=COM, PRI, LOCAL, NET.
- Expand CN=System.
- Expand CN=File Replication Service.
- Expand CN=Domain System Volume (SYSVOL share).
- Right-click the domain controller you are removing, and then click Delete.
- In the DNS console, use the DNS MMC to delete the A record in DNS. The A record is also known as the Host record. To delete the A record, right-click the A record, and then click Delete. Also delete the cname (also known as the Alias) record in the _msdcscontainer. To do so, expand the _msdcs container, right-click the cname, and then clickDelete.
Important If this was a DNS server, remove the reference to this DC under the Name Servers tab. To do this, in the DNS console, right-click the domain name underForward Lookup Zones, click Properties, and then remove this server from theName Servers tab.
Note If you have reverse lookup zones, also remove the server from these zones. - If the deleted computer was the last domain controller in a child domain and the child domain was also deleted, use ADSIEdit to delete the trustDomain object for the child. To do this, follow these steps:
- Click Start, click Run, type adsiedit.msc in the Open box, and then click OK
- Expand the Domain NC container.
- Expand DC=Your Domain, DC=COM, PRI, LOCAL, NET.
- Expand CN=System.
- Right-click the Trust Domain object, and then click Delete.
- Use Active Directory Sites and Services to remove the domain controller. To do this, follow these steps:
- Start Active Directory Sites and Services.
- Expand Sites.
- Expand the server's site. The default site is Default-First-Site-Name.
- Expand Server.
- Right-click the domain controller, and then click Delete.
Advanced optional syntax with the SP1 or later versions of Ntdsutil.exe
Windows Server 2003 SP1 introduced a new syntax that can be used. By using the new syntax, it is no longer required to bind to the DS and select your operation target. To use the new syntax, you must know or obtain the DN of the NTDS settings object of the server that is being demoted. To use the new syntax for metadata cleanup, follow these steps:- Run ntdsutil.
- Switch to the metadata cleanup prompt.
- Run the following commandremove selected serverAn example of this command is as follows.
Note The following is one line but has been wrapped.Remove selected server cn=servername,cn=servers,cn=sitename,cn=sites,cn=configuration,dc= - Remove the cname record in the _msdcs.root domain of forest zone in DNS. Assuming that DC will be reinstalled and re-promoted, a new NTDS Settings object is created by using a new GUID and a matching cname record in DNS. You do not want the DCs that exist to use the old cname record.
As best practice, you should delete the host name and other DNS records. If the lease time that remains on Dynamic Host Configuration Protocol (DHCP) address assigned to offline server is exceeded, another client can obtain the IP address of the problem DC. - If the deleted computer was the last domain controller in a child domain, and the child domain was also deleted, use ADSIEdit to delete the trustDomain object for the child. To do this, follow these steps:
- Click Start, click Run, type adsiedit.msc, and then click OK.
- Expand the Domain NC container.
- Expand DC=Your Domain Name, DC=COM, PRI, LOCAL, NET.
- Expand CN=System.
- Right-click the Trust Domain object,, and then click Delete.
- Use Active Directory Sites and Services to remove the domain controller. To do this, follow these steps:
- Start Active Directory Sites and Services.
- Expand Sites.
- Expand the server's site. The default site is Default-First-Site-Name.
- Expand Server.
- Right-click the domain controller, and then click Delete.
Determine the DN of the server
There are several ways to obtain the DN of the server object that is to be removed. The following example uses Ldp.exe. To obtain the DN by using Ldp.exe, follow these steps:- Run LDP.
- Bind to rootDSE.
- Select View\tree. Base DN should be cn=configuration,dc=rootdomain,dc=
. - Expand Sites.
- Expand the site where the server object resides.
- Expand Servers.
- Expand the server that you are removing.
- Look for a line on the right hand side that starts with DN.
- Copy whole line excluding the DN.
Example snip of the first part of the LDP spew:
Expanding base 'CN=DC1,CN=Servers,CN=Default-First-Site-Name,CN=Sites,CN=Configuration,DC=corp,DC=com'... Result <0>: (null) Matched DNs: Getting 1 entries: >> Dn: CN=DC1,CN=Servers,CN=Default-First-Site-Name,CN=Sites,CN=Configuration,DC=corp,DC=com” What you would copy would be "CN=DC1,CN=Servers,CN=Default-First-Site-Name,CN=Sites,CN=Configuration,DC=corp,DC=com"
Working Domain controller which must be replaced for some reason
- Demote the domain controller using the dcpromo tool. See the Microsoft Knowledge Base Article Q238369 at http://support.microsoft.com/default.aspx?scid=kb;en-us;238369 about how to Promote and Demote Domain Controllers in Windows 2000.
- Install the new domain controller.
- Promote the domain controller using the dcpromo tool. See the Microsoft Knowledge Base Article Q238369 at http://support.microsoft.com/default.aspx?scid=kb;en-us;238369
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