There are several places you may want to look, but "need" is a different story (because Domino doesn't necessarily care about the underlying network specifics).  For example, you can look at the "Fully Qualified Internet Host Name" field on a Server doc.  But, if you weren't using the old domain in that field, then you probably don't need to change that entry.  If you are using Internet Site documents, there's the "Host names or addresses mapped to this site" field on the Basic tab, as well as the "Home URL" field on the Configuration tab.  Are you using Domino to put a standard disclaimer on your mail?  If so, don't forget to change the text to reflect the new domain (if the old domain is currently there).  You might just want to search the address book for "apptechnologies.com" within the various configuration views to see which docs popup with the old domain.  We just went through this process here, so I sympathize.

There are several places you may want to look, but "need" is a different story (because Domino doesn't necessarily care about the underlying network specifics).  For example, you can look at the "Fully Qualified Internet Host Name" field on a Server doc.  But, if you weren't using the old domain in that field, then you probably don't need to change that entry.  If you are using Internet Site documents, there's the "Host names or addresses mapped to this site" field on the Basic tab, as well as the "Home URL" field on the Configuration tab.  Are you using Domino to put a standard disclaimer on your mail?  If so, don't forget to change the text to reflect the new domain (if the old domain is currently there).  You might just want to search the address book for "apptechnologies.com" within the various configuration views to see which docs popup with the old domain.  We just went through this process here, so I sympathize.