Sameer Parwani

I host all my servers with The Planet and a few days back, all at the same time, my MySQL databases started hangin up. The process list (“show processlist”) was showing many many unauthenticated user connections from 192.168.xxx.xxx. MySQL was trying to do a reverse dns lookup on the connecting IP address and was either stalling or failing on the request. I assume something went wrong with the dns server.

The work around is to insert “skip-name-resolve” into your my.cnf file and restart the server and MySQL will no longer run reverse dns on connecting IP addresses. To avoid your facing sudden downtime like mine, I would recommend inserting that line into your my.cnf immediately before you run into the same problem. Of course, if your mysql.user table authenticates any user based on a domain then you can’t skip resolution of IP addresses.