If you have many sub-domain names like
xyz.example.com etc, you can solve these through server-side scripting or other means by using a wildcard A record for *.example.com in your DNS.
How can I determine whether a wildcard domain is configured for any given domain name? Using http://network-tools.com gives a lot of information, but doesn't reveal this. If I need to use commandline tools: I use Windows. One such example that uses a wildcard domain DNS, I think, is blogspot.com.