Why would you be using DHCP on a DirectAdmin based server? DirectAdmin based servers require a static IP# from your upstream and won't be using DHCP, but rather a network configuration you've set up yourself when you installed your OS. This really isn't a DirectAdmin issue.
Are you even running DirectAdmin?
Note that the CentOS subforum is for discussions on DirectAdmin issues specific for CentOS, not for CentOS issues in general.
Jeff