Q. Can the main domain and sub-domain be hosted with two different host or on two different servers ?
Ans: You can host your main domain and sub-domain on two different servers or with two different web hosting companies.
For Example: If you are hosting the main domain in US and if you wish to host its sub-domain on UK server to target UK clients then that’s possible. The main domain can be hosted on US server and the sub-domain on UK server. For this all you need to do is set an A record of the sub-domain where the name servers of the main domain are hosted so that the sub-domain starts resolving from UK server.