AD Replication Troubleshooting

AD Replication Troubleshooting



While not precisely related to your case, I wanted to provide some further information on general troubleshooting of AD Replication issues in domains and forests. The steps and tools below can be used to detect and repair the most common replication issues, and may save you a support call someday. I hope you find these useful!
Troubleshooting Active Directory Replication Problems - http://www.microsoft.com/technet/prodtechnol/windowsserver2003/library/Operations/4f504103-1a16-41e1-853a-c68b77bf3f7e.mspx

A good general guide to deciding how to approach replication failures and break the problem down into its component pieces. It also covers the REPADMIN tool which will be instrumental in seeing error codes that drive how the troubleshooting is done.

Fixing Replication DNS Lookup Problems (Event IDs 1925, 2087, 2088) - http://www.microsoft.com/technet/prodtechnol/windowsserver2003/library/Operations/43e6f617-fb49-4bb4-8561-53310219f997.mspx

The most common cause of replication failure is DNS lookup issues (where we are unable to resolve CNAME records to servers in order to complete the replication ring). This guides an admin through systematically tracking down replication issues caused by DNS, and what sorts of errors mean specific conditions. In Windows Server 2003 SP1 this has been mitigated to some extent, and this is covered in detail in the above article.

Fixing Replication Connectivity Problems (Event ID 1925) - http://www.microsoft.com/technet/prodtechnol/windowsserver2003/library/Operations/7fcaa311-bc19-479d-9a4e-179704dfe08f.mspx

A step-by-step guide to determining replication issues caused by network problems (not related to DNS). This covers simple initial tests like PING and PING -L then moves on to more advanced steps like network tracing.

Fixing Replication Topology Problems (Event ID 1311) - http://www.microsoft.com/technet/prodtechnol/windowsserver2003/library/Operations/062e8eaa-27e0-4c5e-bc2b-2913ecce24b8.mspx

This article covers replication issues caused by issues in the overall site topology, where there is insufficient physical connectivity to complete the replication ring. This means that replication would work fine if the DC's sites and connections were configured more optimally, and there are no other underlying connectivity issues with DNS or the network itself.

How the Active Directory Replication Model Works - http://www.microsoft.com/technet/prodtechnol/windowsserver2003/library/TechRef/1465d773-b763-45ec-b971-c23cdc27400e.mspx

Finally, I wanted to provide more detailed information on how replication actually works. With an understanding of the system and how it operates, it becomes much easier to see where issues are and how to approach troubleshooting them. This guide goes into great detail on USN's, consistency, change notification, scheduling, linked values, and all the other pieces that make up this complex system.