A given client needs to point a domain to my IP. The problem is that when accessing through this subdomain it needs to "drop" at a certain URL.
sub.domainofmyclient.com => mydomain.com/foo/bar
How make this?
PS: Server is VPS with Apache (with WHM/cPanel).
This seems to be a job for a HTTP redirection. You can't do that with DNS.
See the Apache Redirect and Rewrite modules. You will need external redirects.