...

It is very important that network administrators understand DNS.  Here's a great reference to help get more comfortable with DNS: http://en.wikipedia.org/wiki/Domain_name_system.  Even if you think you know everything about it, a refresher is always good.

There is a standalone document on setting up Microsoft DNS Services for use with sipXecs

DNS Records

It is important to understand the difference between A records and SRV records so let's get that out of the way first.

...