Staging / Production Domain for WordPress

My whole Multisite is ready and I am stuck into this problem which is hampering everything.

What I want is to have two different URLs for my site, so that site can be assessed from the staging and from the production too. So basically the site is same, but it has two different domain URLs.

I’ll be very very thankful if you can help me in this.

My site is for e.g. http://www.xyz.com/dir/

I want it to be assessed from http://www.xyz.com/dir
and anotherdomain.xyz.com/dir

Same goes for the admin, two URLs, Same site
http://www.xyz.com/dir/wp-admin
anotherdomain.xyz.com/dir/wp-admin

Many Thanks