How to do a Cname set up?

It's very confusing

[Lorel]

I have a client with a photo gallery set up on another site like this: gallery.example.com (example.com is my client's domain name) but the gallery is hosted elsewhere. A Cname was set up for the domain and gallery was loading ok until we got the website ready to go online and set up the DNS nameservers for the website, then the Website went online, almost instantly, and now the gallery is down.

We can't get any help from the registrar or the gallery site due to the weekend. Can someone explain how this should be set up? I've never dealt with a cname before.

[encyclo]

The "how" really depends on the interface for the DNS settings at your DNS provider - which is usually either the primary hosting company or the domain registrar. Did you change the nameservers to the primary hosting company ones? Do they have a DNS section in their control panel? Anything to manage the zone file?

Also, do you know the target for the CNAME? Usually a CNAME looks like this:

gallery 10800 IN CNAME subdomain.otherprovider.net.

So you need to know what

subdomain.otherprovider.net

should be.