Subdomains on seperate IPs from primary domain

Question

I am assisting a client with swapping his web sites around. In the end, he would like to end up with the primary domain www.domain.org on a separate server (and hence different IP) than several existing aliases of that domain name. Those aliases are in the form alias1.domain.org, alias2.domain.org, etc.. I am calling them aliases because that is currently how they are configured in DNS. EDIT I'm not sure if they are actual CNAME records as I cannot find a record listing in Plesk that specifically includes these.

My question is what should I be considering in terms of DNS for those aliases once the www.domain.org record points to another server. Should those "aliases" be turned into sub-domains?

It almost seems like it would be easier to just change the A record for www.domain.org since all the subs will point to the same (existing) server, but I'm not sure that it can be done that way, although this question makes me think that perhaps it is possible.

If I need to map this out to make it clearer, please let me know. I'm new to posting on SE sites.

Answer 1

This may vary a little bit depending on your registrar, hosting service, and how many "aliases" you have, but here's a general answer to your questions. You're right that the "aliases" (CNAMEs in DNS) would need to be changed, possibly into A records for each pointing to the existing IP. You would then change your primary domain record to the new IP. However, and correct me if I am missing something in your question, if you have a large number of these CNAMEs that will all point to the same location, and you want to keep them the same, you could create a new A record (on your existing IP) and point all of those CNAMEs to that.

The best way to handle this depends on whether you think you'll need to move some of your sub-domains to new IP addresses of their own in the future. If so, you might want to take the time to move them to A records now. However, if you'll want to keep them all the same because of the design of what you're working with, you should probably make the new A record to point all the CNAMEs to.