I'm assuming you are referring to database lookup for name=value pairs.....If you are referring to accessing a remote site via the dotted named convention as opposed to the dotted number convention, then you don't have a problem as you just use the former instead of the latter on the relevant Start Connection call.
There are no direct facilities to access DNS databases (for info lookup) via the CIS API. However, you can access this sort of information via Java. Thus, you will need to write Java applications (those starting with a main method ; not EJBs) in order to use the APIs to access this sort of information.
If you have a look on the CICS Web site, find my paper on LDAP usage which will point you in the right direction -- and include info on configuring a LDAP server for CICS and Websphere access for this type of DNS lookup.
This was first published in March 2003