Fixed Event ID 8457 in Active Directory replication error

Event ID 8457 in Active Directory replication indicates that the destination server is currently rejecting replication requests. Here are steps to troubleshoot and resolve this issue:

1 Verify DNS Configuration:

Ensure that all domain controllers are correctly configured to use the appropriate DNS servers.

Use the nslookup command to verify DNS resolution for all domain controllers.

2. Check Network Connectivity:

Confirm that all domain controllers can communicate with each other over the network. Use the ping command to test connectivity.

3. Run Repadmin Tool:

Use the repadmin tool to diagnose and fix replication issues. Commands like repadmin /showrepl and repadmin /replsummary can help identify the problem areas.

4. Enable Replication:

If replication has been explicitly disabled, you can re-enable it using the following commands:

repadmin /options (DCName) -disable_inbound_repl

repadmin /options (DCName) -disable_outbound_repl

Replace DCName with the name of the domain controller

5. Review Event Logs:

Look at the Directory Service event logs for any related errors that might provide more context about the replication failure.

6. Run DCDIAG Tool:

Use the dcdiag tool to perform a comprehensive health check of your domain controllers. This tool can identify issues that might be affecting replication.

7.Check Time Synchronization:

Ensure that the time is synchronized across all domain controllers. Time discrepancies can cause replication issues. Use the w32tm /query /status command to check the time configuration.