Disable DNS hostname lookup in MySQL
If you never use MySQL authentication by hostname, it is better to disable the DNS hostname lookup for better performance. Especially if you are always connecting from localhost, or authenticate remote host by IP address)
To disable this feature, edit the MySQL configurations, e.g. /etc/my.cnf
[mysqld] ... ... skip-name-resolve
Add the "skip-name-resolve" will do the tricks for you.
Don't forget to restart MySQL to take effect.
# /sbin/service mysqld restart