Here's my setup:
I have an internal network with the domain corp.domain.com. I have a DNS server with two zones; corp.domain.com and domain.com. The corp.domain.com zone has the A records for all of our servers and workstations. The domain.com zone has the A records for www, mail, and other subdomains. We can access all of our subdomains that exist on local servers via our web browsers with no issues.
The problem is with our website. It is not hosted locally, but through GoDaddy. I have A records under the domain.com zone pointing to the IP address provided by GoDaddy. The A records I have setup are www and *.
The website is a Wordpress site, and the only way I have been able to get it to "somewhat" work is to change the Wordpress Address (URL) and Site Address (URL) to be http://www.domain.com instead of http://domain.com. After making this change, I can enter www.domain.com in my browser and it will take me to my externally hosted site, however entering just domain.com will not.
I performed an nslookup on my DNS server and here's the results:
> nslookup domain.com
Address: xxx.xxx.xxx.xxx (IP address for external site)