Yes, you should be concerned. This is telling you the pub's DCDirectory can not communicate with one or more of the subscribers to replicate it's data. This can eventually cause issues with Directory on the pub, best case.
Have you removed or reloaded any subscribers in the cluster recently? If yes then you need to get rid of the old replication agreements. If not you most likely have an issue with name resolution.
I can not stress this enough, MAKE SURE YOU BACKUP DCD & ENSURE YOU HAVE ALL NAME RESOLUTION ISSUES RESOLVED BEFORE YOU UTILIZE THIS PROCEDURE!
Look to this link to resolve your issue. This link needs the CCM releases updated but it IS valid for all 3.x & 4.x versions. If you do not feel comfortable executing then please pen a TAC case, as you have potential to loose all of your directory configuration.:
I'm not able to access my old voice mail messages all of a sudden. The recording says something like 'the message is currently not available'. This has never happened before in all the years I have been using this system. I have t...
If you have 2 ISR routers, one acting as Failover, do we need to have both the same number of SRST licenses on the 2 routers?
No. You will only need the SRST licenses on the primary router. Because this feature...