Demoting a Samba AD DC: Difference between revisions
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= Introduction = |
= Introduction = |
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In certain situations, it is necessary that you permanently remove a domain controller (DC) from Active Directory (AD). While for a regular domain member, you only delete the machine account entry, you have to demote a DC, to remove it from AD. |
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If a DC is not demoted correctly, your AD can get unstable. For example: |
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* replication failures can occur. |
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* the remaining DCs can slow down due to time outs and failed replication attempts. |
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* log ins on domain members can fail or take longer. |
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= Demote a Working Domain Controller = |
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= Demoting an Online Domain Controller = |
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If you domain controller (DC) is still accessible: |
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If the domain controller (DC) to remove is still working correctly: |
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* Log in to the DC you want to demote. |
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* Log in locally to the DC to demote. |
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* Verify that the DC does not hold any FSMO role. See [[Transferring_and_Seizing_FSMO_Roles#Displaying_the_Current_FSMO_Role_Owners|Displaying the Current FSMO Role Owners]]. |
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* Verify that the DC does not own any flexible single master operations (FSMO) roles. See [[Transferring_and_Seizing_FSMO_Roles#Displaying_the_Current_FSMO_Role_Owners|Displaying the Current FSMO Role Owners]]. |
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: In case that the DC owns one or more FSMO roles, transfer them to a different DC. See [[Transferring_and_Seizing_FSMO_Roles#Transferring_an_FSMO_Role|Transferring an FSMO Role]]. |
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* Optionally, display the objectGUID of the DC. For example, for the <code>DC2</code> host: |
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# ldbsearch -H /usr/local/samba/private/sam.ldb '(invocationId=*)' --cross-ncs objectguid | grep -A1 DC2 |
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dn: CN=NTDS Settings,CN=DC2,CN=Servers,CN=Default-First-Site-Name,CN=Sites,CN=Configuration,DC=samdom,DC=example,DC=com |
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objectGUID: c14a774f-9732-4ec2-b9fa-2156c95c4e48 |
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: If you want to verify that all DNS entries were deleted ater you demoted the DC, you need to know the host name, IP address, and the objectGUID of the DC. |
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* Demote the DC: |
* Demote the DC: |
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Line 25: | Line 38: | ||
Asking partner server DC1.samdom.example.com to synchronize from us |
Asking partner server DC1.samdom.example.com to synchronize from us |
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Changing userControl and container |
Changing userControl and container |
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Removing Sysvol reference: CN=DC2,CN=Enterprise,CN=Microsoft System Volumes,CN=System,CN=Configuration,DC=samdom,DC=example,DC=com |
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Removing Sysvol reference: CN=DC2,CN=samdom.example.com,CN=Microsoft System Volumes,CN=System,CN=Configuration,DC=samdom,DC=example,DC=com |
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Removing Sysvol reference: CN=DC2,CN=Domain System Volumes (SYSVOL share),CN=File Replication Service,CN=System,DC=samdom,DC=example,DC=com |
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Removing Sysvol reference: CN=DC2,CN=Topology,CN=Domain System Volume,CN=DFSR-GlobalSettings,CN=System,DC=samdom,DC=example,DC=com |
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Demote successful |
Demote successful |
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* |
* Stop the <code>samba</code> service. |
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* If this DC ran a DNS service for the Active Directory (AD) zones: |
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:* stop the DNS service, if you used the <code>BIND9_DLZ</code> DNS back end. |
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:* verify that domain members and DCs do no longer use this host to resolve the AD DNS zones. |
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= Demote an Offline Domain Controller = |
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= Demoting an Offline Domain Controller = |
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Only follow this procedure if the domain controller (DC) to demote is no longer accessible; for example, due to a hardware failure: |
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In certain situations, such as hardware failures, it is necessary to remove a domain controller (DC) from the domain, that is no longer accessible. In this case, demote the DC using a remaining working Samba DC. |
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* Log in to a remaining DC. |
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{{Imbox |
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* Display your Samba version: |
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| type = important |
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| text = Only run this procedure if the DC to demote is no longer connected to the AD and you cannot demote it as described in [[#Demoting_an_Online_Domain_Controller|Demoting an Online Domain Controller]]. This ensures that all changes, like password changes, are replicated onto another DC. Otherwise such changes would be lost. You can get a list of changes by using [[Samba-tool ldapcmp]]. |
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}} |
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To remotely demote an offline DC: |
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* Log in to a working Samba DC in the Active Directory (AD) forest. |
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* Verify that Samba 4.4 or later is installed: |
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# samba --version |
# samba --version |
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{{Imbox |
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: Samba version prior 4.4.0 do not support demoting a remote DC. Before you continue, upgrade your existing DCs to 4.4.0 or later. For details, see [[Updating_Samba|Updating Samba]]. |
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| type = important |
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| text = You cannot demote an offline remote DC from a DC that runs Samba 4.4 or earlier. Update to Samba 4.4.0 or later before you continue. For details, see [[Updating Samba]]. |
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}} |
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* Verify that the DC to demote does not |
* Verify that the remote DC to demote does not own any flexible single master operations (FSMO) role. See [[Transferring_and_Seizing_FSMO_Roles#Displaying_the_Current_FSMO_Role_Owners|Displaying the Current FSMO Role Owners]]. |
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:* |
:* In case that the DC to demote owns one or more FSMO roles, seize them to the local DC. See [[Transferring_and_Seizing_FSMO_Roles#Transferring_and_Seizing_FSMO_Roles#Seizing_a_FSMO_Role|Seizing an FSMO Role]]. |
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* Verify that the DC to demote is turned off. |
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* To demote a remote DC, for example <code>DC2</code>: |
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* Optionally, display the objectGUID of the DC. For example, for the <code>DC2</code> host: |
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# ldbsearch -H /usr/local/samba/private/sam.ldb '(invocationId=*)' --cross-ncs objectguid | grep -A1 DC2 |
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dn: CN=NTDS Settings,CN=DC2,CN=Servers,CN=Default-First-Site-Name,CN=Sites,CN=Configuration,DC=samdom,DC=example,DC=com |
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objectGUID: c14a774f-9732-4ec2-b9fa-2156c95c4e48 |
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: If you want to verify that all DNS entries were deleted ater you demoted the DC, you need to know the host name, IP address, and the objectGUID of the DC. |
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* Demote the remote DC. For example, to demote <code>DC2</code>: |
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# samba-tool domain demote --remove-other-dead-server=DC2 |
# samba-tool domain demote --remove-other-dead-server=DC2 |
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Line 80: | Line 121: | ||
Removing Sysvol reference: CN=DC2,CN=Topology,CN=Domain System Volume,CN=DFSR-GlobalSettings,CN=System,DC=samdom,DC=example,DC=com |
Removing Sysvol reference: CN=DC2,CN=Topology,CN=Domain System Volume,CN=DFSR-GlobalSettings,CN=System,DC=samdom,DC=example,DC=com |
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{{Imbox |
:{{Imbox |
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| type = warning |
| type = warning |
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| text = |
| text = You must not reconnect a DC to the network, that was demoted remotely. Your AD can get inconsistent. |
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}} |
}} |
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* If the demoted DC ran a DNS service for the Active Directory (AD) zones, verify that domain members and DCs no longer use this host to resolve the AD DNS zones. |
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Line 91: | Line 134: | ||
= Verifying the Demotion = |
= Verifying the Demotion = |
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To manually verify that the domain controller (DC) was successfully demoted: |
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The following steps are to verify and clean up remaining directory information after a domain controller demotion. It does not replace the procedure for the demote itself! |
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{{Imbox |
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| type = important |
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| text = The steps described in this section, do not replace the official demote procedures described in the previous sections. The steps in this section are only to verify and to manually remove remaining entries, if the official demote process failed. |
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}} |
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* Log in to a Windows domain member using an account that is member of the <code>Domain Admins</code> group, such as the AD domain Administrator account. |
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* Install the Remote Server Administration Tools (RSAT). For details, see [[Installing RSAT]]. |
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* Open the <code>Active Directory Users and Computers</code> application. |
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:* Navigate to the <code>Domain Controllers</code> entry and verify that the demoted DC was removed. For example: |
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:[[Image:ADUC_Domain_Controllers.png]] |
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:* If the entry is still listed, you can manually remove it: |
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::* Right-click to the DC entry and select <code>Delete</code> |
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::* Click <code>Yes</code> to confirm. |
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::* Select <code>Delete this Domain Controller anyway. It is permanently offline and can no longer be removed using the removal wizard.</code> and click <code>OK</code>. |
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::* If the DC is a global catalog server, click <code>Yes</code> to confirm. |
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* Open the <code>Active Directory Sites and Services</code> application and verify that the demoted DC is no longer listed in any Active Directory (AD) site entry. For example: |
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* Log on as Domain Administrator to a Windows computer having the Microsoft Remote Server Administration Tools (RSAT) installed. See [[Installing_RSAT|Installing RSAT]. |
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:[[Image:ADSS_Domain_Controllers.png]] |
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:* If the entry is still listed, you can manually remove it: |
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::* Right-click to the DC entry and select <code>Delete</code> |
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::* Click <code>Yes</code> to confirm. |
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* Open the <code>DNS</code> application and verify that the DC's host name, IP address, and objectGUID is no longer used in any DNS entry in any AD DNS zone. For example: |
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* Start <code>Active Directory Users and Computers</code>, navigate to the <code>Domain Controllers</code> container and verify that the demoted DC was removed. |
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:[[Image:DNS_Domain_Controllers.png]] |
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:* If entries are still listed, you can manually remove them: |
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::* Right-click to the entry and select <code>Delete</code> |
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::* Click <code>Yes</code> to confirm. |
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: [[Image:ADUC_Domain_Controllers.png]] |
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* Start <code>Active Directory Sites and Services</code> and check that the demoted DC is not listed in any site. |
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: [[Image:ADSS_Domain_Controllers.png]] |
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* Start the <code>DNS</code> MMC console and check in <u>all</u> zones, that no entry referring to the demoted DC or it's IP has been left. |
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---- |
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: [[Image:DNS_Domain_Controllers.png]] |
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[[Category:Active Directory]] |
Revision as of 02:53, 31 July 2019
Introduction
In certain situations, it is necessary that you permanently remove a domain controller (DC) from Active Directory (AD). While for a regular domain member, you only delete the machine account entry, you have to demote a DC, to remove it from AD.
If a DC is not demoted correctly, your AD can get unstable. For example:
- replication failures can occur.
- the remaining DCs can slow down due to time outs and failed replication attempts.
- log ins on domain members can fail or take longer.
Demoting an Online Domain Controller
If the domain controller (DC) to remove is still working correctly:
- Log in locally to the DC to demote.
- Verify that the DC does not own any flexible single master operations (FSMO) roles. See Displaying the Current FSMO Role Owners.
- In case that the DC owns one or more FSMO roles, transfer them to a different DC. See Transferring an FSMO Role.
- Optionally, display the objectGUID of the DC. For example, for the
DC2
host:
# ldbsearch -H /usr/local/samba/private/sam.ldb '(invocationId=*)' --cross-ncs objectguid | grep -A1 DC2 dn: CN=NTDS Settings,CN=DC2,CN=Servers,CN=Default-First-Site-Name,CN=Sites,CN=Configuration,DC=samdom,DC=example,DC=com objectGUID: c14a774f-9732-4ec2-b9fa-2156c95c4e48
- If you want to verify that all DNS entries were deleted ater you demoted the DC, you need to know the host name, IP address, and the objectGUID of the DC.
- Demote the DC:
# samba-tool domain demote -Uadministrator Using DC1.samdom.example.com as partner server for the demotion Password for [SAMDOM\administrator]: Deactivating inbound replication Asking partner server DC1.samdom.example.com to synchronize from us Changing userControl and container Removing Sysvol reference: CN=DC2,CN=Enterprise,CN=Microsoft System Volumes,CN=System,CN=Configuration,DC=samdom,DC=example,DC=com Removing Sysvol reference: CN=DC2,CN=samdom.example.com,CN=Microsoft System Volumes,CN=System,CN=Configuration,DC=samdom,DC=example,DC=com Removing Sysvol reference: CN=DC2,CN=Domain System Volumes (SYSVOL share),CN=File Replication Service,CN=System,DC=samdom,DC=example,DC=com Removing Sysvol reference: CN=DC2,CN=Topology,CN=Domain System Volume,CN=DFSR-GlobalSettings,CN=System,DC=samdom,DC=example,DC=com Demote successful
- Stop the
samba
service.
- If this DC ran a DNS service for the Active Directory (AD) zones:
- stop the DNS service, if you used the
BIND9_DLZ
DNS back end. - verify that domain members and DCs do no longer use this host to resolve the AD DNS zones.
- stop the DNS service, if you used the
Demoting an Offline Domain Controller
In certain situations, such as hardware failures, it is necessary to remove a domain controller (DC) from the domain, that is no longer accessible. In this case, demote the DC using a remaining working Samba DC.
Only run this procedure if the DC to demote is no longer connected to the AD and you cannot demote it as described in Demoting an Online Domain Controller. This ensures that all changes, like password changes, are replicated onto another DC. Otherwise such changes would be lost. You can get a list of changes by using Samba-tool ldapcmp. |
To remotely demote an offline DC:
- Log in to a working Samba DC in the Active Directory (AD) forest.
- Verify that Samba 4.4 or later is installed:
# samba --version
You cannot demote an offline remote DC from a DC that runs Samba 4.4 or earlier. Update to Samba 4.4.0 or later before you continue. For details, see Updating Samba. |
- Verify that the remote DC to demote does not own any flexible single master operations (FSMO) role. See Displaying the Current FSMO Role Owners.
- In case that the DC to demote owns one or more FSMO roles, seize them to the local DC. See Seizing an FSMO Role.
- Verify that the DC to demote is turned off.
- Optionally, display the objectGUID of the DC. For example, for the
DC2
host:
# ldbsearch -H /usr/local/samba/private/sam.ldb '(invocationId=*)' --cross-ncs objectguid | grep -A1 DC2 dn: CN=NTDS Settings,CN=DC2,CN=Servers,CN=Default-First-Site-Name,CN=Sites,CN=Configuration,DC=samdom,DC=example,DC=com objectGUID: c14a774f-9732-4ec2-b9fa-2156c95c4e48
- If you want to verify that all DNS entries were deleted ater you demoted the DC, you need to know the host name, IP address, and the objectGUID of the DC.
- Demote the remote DC. For example, to demote
DC2
:
# samba-tool domain demote --remove-other-dead-server=DC2 Removing nTDSConnection: CN=04baf417-eb41-4f31-a5f1-c739f0e92b1b,CN=NTDS Settings,CN=DC1,CN=Servers,CN=Default-First-Site-Name,CN=Sites,CN=Configuration,DC=samdom,DC=example,DC=com Removing nTDSDSA: CN=NTDS Settings,CN=DC2,CN=Servers,CN=Default-First-Site-Name,CN=Sites,CN=Configuration,DC=samdom,DC=example,DC=com (and any children) Removing RID Set: CN=RID Set,CN=DC2,OU=Domain Controllers,DC=samdom,DC=example,DC=com Removing computer account: CN=DC2,OU=Domain Controllers,DC=samdom,DC=example,DC=com (and any child objects) Removing Samba-specific DNS service account: CN=dns-DC2,CN=Users,DC=samdom,DC=example,DC=com updating samdom.example.com keeping 3 values, removing 1 values updating DC=_kerberos._tcp.Default-First-Site-Name._sites,DC=samdom.example.com,CN=MicrosoftDNS,DC=DomainDnsZones,DC=samdom,DC=example,DC=com keeping 1 values, removing 1 values updating DC=_ldap._tcp.Default-First-Site-Name._sites,DC=samdom.example.com,CN=MicrosoftDNS,DC=DomainDnsZones,DC=samdom,DC=example,DC=com keeping 1 values, removing 1 values updating DC=_gc._tcp.Default-First-Site-Name._sites,DC=samdom.example.com,CN=MicrosoftDNS,DC=DomainDnsZones,DC=samdom,DC=example,DC=com keeping 1 values, removing 1 values updating DC=_kerberos._tcp,DC=samdom.example.com,CN=MicrosoftDNS,DC=DomainDnsZones,DC=samdom,DC=example,DC=com keeping 1 values, removing 1 values updating DC=_kerberos._udp,DC=samdom.example.com,CN=MicrosoftDNS,DC=DomainDnsZones,DC=samdom,DC=example,DC=com keeping 1 values, removing 1 values updating DC=_kpasswd._tcp,DC=samdom.example.com,CN=MicrosoftDNS,DC=DomainDnsZones,DC=samdom,DC=example,DC=com keeping 1 values, removing 1 values updating DC=_kpasswd._udp,DC=samdom.example.com,CN=MicrosoftDNS,DC=DomainDnsZones,DC=samdom,DC=example,DC=com keeping 1 values, removing 1 values updating DC=_ldap._tcp,DC=samdom.example.com,CN=MicrosoftDNS,DC=DomainDnsZones,DC=samdom,DC=example,DC=com keeping 1 values, removing 1 values updating DC=_gc._tcp,DC=samdom.example.com,CN=MicrosoftDNS,DC=DomainDnsZones,DC=samdom,DC=example,DC=com keeping 1 values, removing 1 values updating DC=_ldap._tcp.4d5258b9-0cd7-4d78-bdd7-99ebe6b19751.domains,DC=_msdcs.samdom.example.com,CN=MicrosoftDNS,DC=ForestDnsZones,DC=samdom,DC=example,DC=com keeping 1 values, removing 1 values updating DC=_kerberos._tcp.Default-First-Site-Name._sites.dc,DC=_msdcs.samdom.example.com,CN=MicrosoftDNS,DC=ForestDnsZones,DC=samdom,DC=example,DC=com keeping 1 values, removing 1 values updating DC=_ldap._tcp.Default-First-Site-Name._sites.dc,DC=_msdcs.samdom.example.com,CN=MicrosoftDNS,DC=ForestDnsZones,DC=samdom,DC=example,DC=com keeping 1 values, removing 1 values updating DC=_ldap._tcp.Default-First-Site-Name._sites.gc,DC=_msdcs.samdom.example.com,CN=MicrosoftDNS,DC=ForestDnsZones,DC=samdom,DC=example,DC=com keeping 1 values, removing 1 values updating DC=c14a774f-9732-4ec2-b9fa-2156c95c4e48,DC=_msdcs.samdom.example.com,CN=MicrosoftDNS,DC=ForestDnsZones,DC=samdom,DC=example,DC=com keeping 0 values, removing 1 values updating DC=_kerberos._tcp.dc,DC=_msdcs.samdom.example.com,CN=MicrosoftDNS,DC=ForestDnsZones,DC=samdom,DC=example,DC=com keeping 1 values, removing 1 values updating DC=_ldap._tcp.dc,DC=_msdcs.samdom.example.com,CN=MicrosoftDNS,DC=ForestDnsZones,DC=samdom,DC=example,DC=com keeping 1 values, removing 1 values updating DC=_ldap._tcp.gc,DC=_msdcs.samdom.example.com,CN=MicrosoftDNS,DC=ForestDnsZones,DC=samdom,DC=example,DC=com keeping 1 values, removing 1 values Removing Sysvol reference: CN=DC2,CN=Enterprise,CN=Microsoft System Volumes,CN=System,CN=Configuration,DC=samdom,DC=example,DC=com Removing Sysvol reference: CN=DC2,CN=samdom.example.com,CN=Microsoft System Volumes,CN=System,CN=Configuration,DC=samdom,DC=example,DC=com Removing Sysvol reference: CN=DC2,CN=Domain System Volumes (SYSVOL share),CN=File Replication Service,CN=System,DC=samdom,DC=example,DC=com Removing Sysvol reference: CN=DC2,CN=Topology,CN=Domain System Volume,CN=DFSR-GlobalSettings,CN=System,DC=samdom,DC=example,DC=com
You must not reconnect a DC to the network, that was demoted remotely. Your AD can get inconsistent.
- If the demoted DC ran a DNS service for the Active Directory (AD) zones, verify that domain members and DCs no longer use this host to resolve the AD DNS zones.
Verifying the Demotion
To manually verify that the domain controller (DC) was successfully demoted:
The steps described in this section, do not replace the official demote procedures described in the previous sections. The steps in this section are only to verify and to manually remove remaining entries, if the official demote process failed. |
- Log in to a Windows domain member using an account that is member of the
Domain Admins
group, such as the AD domain Administrator account.
- Install the Remote Server Administration Tools (RSAT). For details, see Installing RSAT.
- Open the
Active Directory Users and Computers
application.
- Navigate to the
Domain Controllers
entry and verify that the demoted DC was removed. For example:
- Navigate to the
-
- If the entry is still listed, you can manually remove it:
- Right-click to the DC entry and select
Delete
- Click
Yes
to confirm. - Select
Delete this Domain Controller anyway. It is permanently offline and can no longer be removed using the removal wizard.
and clickOK
. - If the DC is a global catalog server, click
Yes
to confirm.
- Right-click to the DC entry and select
- Open the
Active Directory Sites and Services
application and verify that the demoted DC is no longer listed in any Active Directory (AD) site entry. For example:
-
- If the entry is still listed, you can manually remove it:
- Right-click to the DC entry and select
Delete
- Click
Yes
to confirm.
- Right-click to the DC entry and select
- Open the
DNS
application and verify that the DC's host name, IP address, and objectGUID is no longer used in any DNS entry in any AD DNS zone. For example:
-
- If entries are still listed, you can manually remove them:
- Right-click to the entry and select
Delete
- Click
Yes
to confirm.
- Right-click to the entry and select