Quick domain-controller replication check

Short answer Check domain-controller replication summary and error details with two focused queries.

When to use it

When AD, GPO, user or group changes differ between domain controllers.

Summary

repadmin /replsummary
repadmin /showrepl * /errorsonly

Note

Focus on failures and highest delta.

PowerShell errors

Get-ADReplicationPartnerMetadata -Target * -Scope Forest | Where-Object {$_.LastReplicationResult -ne 0} | Select-Object Server,Partner,LastReplicationAttempt,LastReplicationResult

Note

Any nonzero result is an error code.

Caution

Do not reflexively force synchronization before fixing DNS, time or connectivity causes.