Tag not monitored by Microsoft.
Hello Noyon Chandra Das,
From your screenshot, this looks like an exchange server. Correct me if I am wrong.
Is this a case with only this server or similar exchange servers? Were you able to notice this in any other server, other than exchange?
Trying to figure out if it in case any indirect authentications like Autodiscover or activesync might cause these entries in the logs, resulting in this number. Confirming the pattern might help address here.