I'm really a newbie about this issues so excuse me if this is a rather dumb question, I'm trying to point a domain a client of mine bought to a sub-domain of mine, they're both from different companies, I'm not looking for a redirect but instead let's say his domain is www.clientdomain.com and mine is www.mydoamin.com I need to point dev.clientdomain.com to test.mydomain.com for example keeping the URL as it is, so when I visit the 'about' page it'd be dev.clientdomain.com/about instead of test.mydomain.com/about.
I hope it makes some sense, I have seen this done before but have no idea if its using .htaccess files or changing some configuration options in the host control panel, if so I assume each host has their way of doing this so a general example would be great to point me in the right direction.
Thanks in advance!