Information
The SystemLog.quiet option stops logging of information such as:
 connection events
 authentication events
 replication sync activities
 evidence of some potentially impactful commands being run (eg: drop, dropIndexes, validate)
This information should be logged whenever possible. This check is only for Enterprise editions.
Rationale:
The use of SystemLog.quiet makes troubleshooting problems and investigating possible security incidents much more difficult.
Solution
Set SystemLog.quiet to false in the /etc/mongod.conf file to disable it.