On a recent project a disaster recovery site was configured with a single-node standby cluster. This standby cluster was configured as the SCR target, the source being a CCR environment at the production data center. I noted the following event log entry that was logged on a regular basis on the standby cluster node:
Description: Exchange couldn’t read the configuration from the Active Directory directory service because of error: Microsoft.Exchange.Common.ExClusTransientException...etc
The error goes on to reference ExCluster.GetActiveCMSOnNode. Clearly there is no Clustered Mailbox Server (CMS) on the single passive node of a standby cluster so this event log can be safely ignored. Of course, if you want to stop the noise being generated in the event log you should disable the transport log search service on this node. However, do remember to re-enable this service in a site resilience scenario.