Well configured name resolution is very important for DA, and can be challenging to figure out. Assuming you have a domain configured in your network, you certainly have DNS setup, but for DA, it also has to support AAAA records so the DA clients can register themselves. There are plenty of DNS servers out there that support IPv6, such as BIND 9 , but if you choose to go with Microsoft DNS, it's going to have to be version 2003 or later.
Another aspect of DNS with regards to DA is the matter of internal vs. external name resolution. Your DA clients will have to be able to correctly resolve the public hostname of your UAG server, or your server array. They will also need to be able to resolve the public URLs of the IP-HTTPS certificate CDP URLs on the internet. While connected to the corporate network, the clients will have to be able to resolve the NLS server, and when they establish the DA connection, resolve names of internal servers they need to contact.
If...