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Hello!
While troubleshooting a replication issue with my domain controllers today I've been puzzled by several questions that came into my mind and to which I don't currently have answers. Please help me clarify the following:
I have a script that daily reports the repadmin /replsummary ... information and the delta shown in those reports were usually between 1m-58m (including yesterday, 10/18/2022) but today the reports started looking differently (the reports from domain controller KM02, host names have been changed for the picture):
Q1) How come the today's delta is >60 days for KM02 (and also for VM-DC-01) if this delta was only 52m yesterday? I thought that if the problem - for example - has appeared yesterday (10/18/22) at ~10AM then the delta can't be more that 1 day... ???
Q2) Doesn't it look strange that there's a DNS lookup error for VM-DC-01 in the Source section but no errors in the Destination section of the report?
Q3) The main theory question: this article says:
*/bydest
Summarizes the replication status for all domain controllers that a given destination domain controller replicates from. This parameter does not display the source domain controller.*
Thank you in advance,
Michael
Hi Mikhail,
As the tools is unable to connect to the destination server, the last replication time will be unknown and probably the reason why the delta has jumped from hours to days.
The same is probably true about the Km02 error, the tools is probably try to connect the server and it fails and returns an error while checking the replication details and is just displaying the error. I would suggest fixing the name resolution issue first and see what results you get then.
Gary.
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Might also check the System and DFS Replication event logs for clues.
--please don't forget to upvote and Accept as answer if the reply is helpful--
Hi DSPatrick,
Thank you - I'll check them!
Sounds good, please don't forget to close up the thread by 
Just checking if there's any progress or updates?
--please don't forget to upvote and Accept as answer if the reply is helpful--
Hi all,,
"As the tools is unable to connect to the destination server, the last replication time will be unknown and probably the reason why the delta has jumped from hours to days." - agree, I also thought about it!
The thing that bothers me the most is that I don't understand the theory itself:
"*/bydest
Summarizes the replication status for all domain controllers that a given destination domain controller replicates from. This parameter does not display the source domain controller.*
What does mean
"Destination DSA
KM02 > 60days... The RPC server is unavailable."
...in the repadmin's output on KM02 itself? According to "the replication status for all domain controllers that a given destination domain controller replicates from" it means KM02 was trying to replicate from KM02 and failed because of the RPC error - complete nonsence :(((
Agreed, but as you are in a failure state the result are probably known.
The other thing to bear in mind the switch only changes what is displayed, the tools probably still need to run the tests against the selected servers, including itself to get the details but the error seems to be causing erroneous information to be displayed.
Part of this information will come from the replication cursors that we looked at in one of your previous questions about replication intervals I think. The details of the failure does come from one of the replication APIs.
Gary
I understand, thank you very much for the help!
...will keep trying to understand what does the "RPC server is unavailable" error mean providing that those DCs are connected to the same switch and can "ping/rdp/smb" each other without single issue... :(
Regards,
Michael
The error is normally as a result of the DsGetDcName api failing to find the details of the requested dc, which usually as a result of a dns issue or ports being blocked. You can use the posts below to check the name resolution and check that the ports are open.
