We have our own internal DNS server inside our network on our domain. I just changed the nameservers of a bunch of our domain names through our registrar. Now on my home PC (off the network) the changes were almost immediate. How ever inside our network the changes are not immediate. In fact I went into my DNS Manager and I have a few of these domains setup as zones (not all of them) and I notice the records still have the old IP address of the old namespace, and the timestamp is STATIC. Will I have to manually edit these or can they somehow be automatically updated like everything else once the DNS has propgated on the internet.
If the timestamp is static then I'm going to assume you entered them manually into your DNS server? If so you will need to modify them by hand.
From what I'm seeing in comments, you are making static A records for your domain inside which is the same outside (mydomain.com).
This is a common problem when creating a domain inside your network with a publicly addressable domain, this is why people have domains specified as .local to avoid the problems of using a .com inside their network. It's the same reason there are private ip ranges (192.168.0.0|172.16.0.0|10.0.0.0) so you avoid the problems of routing public ip addresses in and outside your network.