Server 2003 DNS redirecting

[q2418130103p]

Hello all,
Some of the mobile devices on our network occasionly leave the building. Becuase of this we use a DynDNS on all the mobile devices. When the devices come back into the building the sometimes have trouble accessing things on the local network because they are still using the DynDNS which is directing their traffic out of the building and back in again.

Is there a way to make a manual entry in our DNS server that will redirect all connections made to our DynDNS to point directly to the server for devices that are in the building only of coarse.

When I go to create a HOST record of a CNAME it automactly trys to append our local netowkrs domain name to the end of the host name, which is obviously not correct when dealing with the DynDNS entry.