A new feature is Dynamic DNS (DDNS) and as you begin to find out more about how name resolution and service location works, it's a feature you'll be quite thankful for. The basic premise behind DNS is that when a client starts it will register its name-to-IP address mapping with the DNS server that it's configured with. This is a giant change from NT 4.0 when administrators had to enter in all DNS records manually. DDNS works similarly to how WINS worked in NT 4.0 where most, if not all, clients were registered dynamically.
The
Domain Name System (DNS) is a distributed Internet directory service. DNS
is used mostly to translate between domain names and IP addresses, and to
control Internet email delivery. Most Internet services rely on DNS to
work, and if DNS fails, web sites cannot be located and email delivery
stalls.
Setting up DNS if you are a server admin, web master, web hosting service
owner or similar can be a very difficult task. If you are new to it you
will most probably have to read a book before being able to set DNS up
without errors, if you are experienced you are without doubt very very
tired of editing text files and updating serial numbers over and over
again.
In NT 4.0 we would located certain resources on the network like domain controllers through what is commonly referred to as the 16th character of the NetBIOS name or the NetBIOS suffix. Based on this identification we could determine if a machine was a domain controller, master browser, etc.
However, in Windows 2000 we now locate many network resources through special DNS records called SRV records. Here's an easy way to see the impact of this change. Find a machine running Active Directory (or install one if you must!), install DNS and turn Dynamic Updates on if they aren't already (search the on-line help for how to do this). After a while you'll see a huge number of records listed in your DNS zone. Most of those are SRV records. Now imagine trying to add, modify and/or delete all of those records by hand!
DDNS is not 100% required for Active Directory, but if you don't employ DDNS, plan on having a couple of people dedicated solely to changing SRV records in a medium to large organization. Not a very smart use of resources nor a very fun job! Also, be sure to plan for DDNS is you employ UNIX servers run BIND to do your host name resolution. Technically, BIND version 8.1.1 will support DDNS but you should really plan on going with at least 8.2.2 or higher to get a stable, feature-rich version of BIND.