How to solve problems with CNAME and accessing your subdomain

If you can’t access your website via the domain name you have set up when in your own network, but it works fine for everybody else outside your network (including you from home or elsewhere), then the chances are you have a problem with your internal name server.

You might see the following error:

CNAME problem

Name servers are the way a computer goes from a human-friendly domain name – such as – to a machine-friendly IP address such as Most of these name servers are on the internet, telling the world what they know about domain names. Sometimes, however, you might also have a name server on an internal network to deal with computers on your network, asking about other computers on your network. These are only ever accessible from your own network because they only ever have information on your network.

The issue arises because quite often your own network might be named after your company. For example, your internal network might be called This can occasionally cause problems. The way to solve this is quite simple. Whoever manages your network just needs to update the local name server with the new information. Just drop them a line saying something like the following and they should be able to fix the issue almost immediately:

Hi I.T. friend!

Can you please update our internal name server so that is a cname referring to . The public DNS works for everybody else but it’s not working on our network.

Thanks for your help!

Why does this problem happen?

The name server on your network will think it is authoritative for your domain. This means that it will never ask a different computer if it doesn’t know the answer. If you ask it about something it doesn’t know about, it will tell you authoritatively that no such computer exists. So the computer telling the rest of the internet about your subdomain will never be asked, so you will never be told the right answer.