I need to be able to locate our mail server using dns internally with its internal ip being returned (ie:

The existing dns records point to the external ip address (ie: this info is returned internally and externally. It must remain externally available

Can what I require be done ?

Do I need to set up a second zone ? if so what do I use as our domain name in the second zone (ie: DN is xxx.xx.xc do I need to use a diferent DN ie: internal.xxx.xx.xc)

Any help will be appreciated.