Event ID - 2121

Event Id2121
Description"Process <process name> (PID=<process id>). DSAccess is unable to connect to any domain controller in domain <name> althoughDNS was successfully queried for the service location (SRV) resource record used to locate a domain controller for that domain. The query was for the SRV record for <name> The following domain controllers were identified by the query: <distinguished name> "
Event InformationAccording to Microsoft:
This event occurs if Diagnostics Logging on the Topology category of DSAccess is set to Minimum for the server. This event means that the domain controllers from the specified domain will not be used by DSAccess. As long as there is sufficient capacity in suitable domain controllers in other domains, it will not cause mail flow interruption. However, it is recommended that this event be investigated and fixed as soon as possible. If the event contains the name of the local domain, topology discovery cannot be completed, and this will cause mail flow interruption. The following are the possible causes:
1. The required A (address) resource records that map the name of the domain controllers to their IP address do not exist in DNS.
2. The domain controllers advertised in DNS might not be connected to the network or are connected to the network but are not running
User Action :
1. Verify that the required A resource records exist in DNS by using the Nslookup command-line tool.
2. Verify connectivity to the domain controller and then verify that the domain controller is running.
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