So, this might be a tricky one to sort out, but I'll give it a try.
We provide a number of websites to clients, and we do all of the work in designing and creating the sites, so that's all fine. The only thing our clients have to do is create a sub-domain of their main domain name and point it to our server (since most of our clients already have their own site, and what we provide is just an 'extra').
We had one client set up the subdomain yesterday (26 hours ago at time of writing), but it's not resolving yet. It's a new subdomain, and we're just getting the 'Server not found' error. So, we assumed it's just not propagated yet.
Then we got word from another client (completely unrelated to the other) a couple of hours ago who set their sub-domain up over a week ago. Exactly the same error.
We've checked everything we can our side, but since the sub-domain doesn't resolve to our IP (or, in fact, to any IP), I doubt there's a lot we can do.
The sub-domains we're checking should be correct because the client sent us a screenshot of their DNS admin page when they were setting it up, and they've spelt it correctly.
Looks like they created an A record, pointing to our IP address.
But since we don't have access to the actual DNS settings, we can't really investigate further.
So...anybody got any ideas what could be up? I know it's difficult not knowing their exact setup, and what they've done to create the sub-domain, but something just doesn't seem right. If it was just one client having this problem, fine, it must be something that the client's done wrong. But we got two clients do the same thing, and have the same problem.