MySQL not resolving IP to hostname to check for priviliges

I'm testing our backups and I'm running into problems with the mysql accounts. I can't log in from one (restored) server to another (restored) mysql server. The logs show me that it's denying the user 'apache_auth'@192.168.0.120, whereas on the priviliges table the user is in as 'apache_auth'@myhost.internal.example.com. However if I ping myhost.internal.example.com from the mysql server, i can see that it's getting the IP address of 192.168.0.120. How come it's not doing the reverse?

From serverfault Rory McCann

• Check your MySQL config file (like /etc/my.cnf) and see if your db server has skip-name-resolve enabled. More info: http://dev.mysql.com/doc/refman/5.0/en/dns.html

  Also, tail the error log (specified and enabled by log-error) or the warning log (log-warnings). More info: http://dev.mysql.com/doc/refman/5.0/en/server-options.html. I don't remember which one of them would have logs on denied access.

  From Artem Russakovskii

• This was my own fault. we're using an internal 192.168.0.x network, with our own nameserver to resolve 'db1' to 192.168.0.x. However I haven't set up the reverse ARPA / PTR entries. Which obviously means it's not resolveing IP addresses.

  From Rory McCann