Inbound Replication

Shows inbound replication from DCs in the same site as the DC you ran the command on. Also show the DCs object GUID which you may need for other replication related commands
repadmin /showreps

Lingering Objects

Lingering objects can cause a myriad of replication problems. Event IDs 1388 or 1988 in the Directory Service event log will indicate if there are lingering objects preventing replication to or from a specific DC. You can also use the replmon.exe gui application to see if there are replication issues to or from a specific DC.

You can use the following command to identify lingering objects on a DC where <ServerName> is the name of the DC that has the lingering objects, <ServerGUID> is the GUID of a DC that is currently up to date, and <DirectoryPatition> is the DN of the Active Directory partition that contains the lingering objects (Configuration, Domain, Schema). The lingering objects will be logged in the Directory Service log on the DC specified by <ServerName>. To actually remove the lingering objects, just remove the /advisory_mode switch.
repadmin /removelingeringobjects <ServerName> <ServerGUID> <DirectoryPartition> /advisory_mode

Replication Storm and Corrupted FRS Database

Recently some of my colleagues in another department did an application upgrade to an application that stores some EXEs used during logon in the netlogon share on our DCs. For some still unknown reason one of the EXEs would be deleted from netlogon and begin replicating that deletion. Then my colleagues would see that the particular EXE was missing from the DCs that had already replicated the deletion and they would copy the EXE back to the DCs that were missing it simultaneously. After doing this a few times a replication storm of creates and deletes was looping through all of our DCs. We had no choice but to stop FRS on all the DCs and perform a D4/D2 restore on each domain controller. We found the few articles below particularly useful as well as these tools: FRSDiag and Sonar

Using the Burflags registry key to reinitialize File Replication Service replica sets
How to rebuild the SYSVOL tree and its content in the domain
Folder name is changed to FolderName_NTFRS_xxxxxxxx

Replication Summary

Shows the replication summary for whatever DC you ran the command on by both source and destination. Meaning when the last replication from the DC you ran the command on was and when the last replication to the DC you ran the command on was
repadmin /replsum /bysrc /bydest /sort:delta

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