From fixing time sync drama and lingering AD ghosts to dealing with firewall blockades and stale Knowledge Consistency Checker (KCC) caches, this guide has all the tips you need.
The configuration of how data is replicated between different servers is incorrect.
Open Command Prompt as an administrator and run "repadmin /showrepl" to identify replication failures.
Use Active Directory Sites and Services to review site links and bridgehead servers.
If the topology is a mess, run the KCC with "repadmin /kcc" in Command Prompt to fix it.
Use the following to verify using the following command "bash dcdiag/test:replications"
Your computer's system clock has not been able to synchronize with a reliable time source (like an internet time server) for a specified number of seconds
Check time synchronization.
Remember: AD hates tardiness. Keep the time gap under five minutes using the command "net time /domain", or it throws a fit.
A deleted object is haunting your DC. This usually occurs when a DC is disconnected during the deletion process.
Use "repadmin /removelingeringobjects" to exorcize those ghosts.
Replace:
To prevent future haunting, ensure proper tombstone lifetime settings in AD.
Run the following PowerShell command to verify tombstone lifetime:
"Get-ADObject -Filter -SearchBase "CN=Directory Service,CN=Windows NT,CN=Services,CN=Configuration,DC=domain,DC=com" -Properties tombstoneLifetime"
If needed, modify it using: "Set-ADObject -Identity "<DN>" -Replace @{tombstoneLifetime=<Days>}"
The DNS record of a specific computer or a service is not being replicated across all domain controllers.
Verify SRV records using "nslookup" or "dcdiag/test:dns".
Run the following to check DNS records: "nslookup -type=srv ldap._tcp.dc._msdcs.
Reregister DNS records
Open the Command Prompt as an administrator and run the following command: "ipconfig /registerdns".
Restart the Netlogon service to trigger automatic DNS updates using the following command "net stop netlogon && net start netlogon"
The DC cannot synchronize data with other DCs usually due to a connectivity or network topology issue preventing it from reaching any replication partners.
Review bridgehead server assignments in Active Directory Sites and Services.
Distribute the load by assigning additional bridgehead servers.
A happy bridgehead means smoother replication traffic. Monitor Performance using tools like "repadmin/showrepl".
