Paul,
You can be comfortable using Microsoft's DNS on NT 4.0 so long as you apply SP6 and set the timeouts, etc. correctly.
Prior to SP6, DNS experienced various problems all the way from "not releasing expired leases" to "issuing the same IPaddress to more than one host". Microsoft rated all of these problems as minor but, as a systems administrator, you know that you cannot live with these types of problems.
SP6 seems to have fixed all of the known problems with Microsoft's DNS. The user interface is very easy to use. Setting up a primary/secondary or master/slave relationship between servers is very easy to do. All of the zone files are individual files with a .dns extension under the /winnt/system/dns folder. These files can be edited with a text editor if you prefer. They can even be moved between servers but, keep in mind that just placing a .dns file on a server will NOT cause the DNS service to automatically serve this zone. You must use the DNS interface to register the zone with the service before the zone file will be read.
Also, the DNS service uses an Access-like database (Thanks Microsoft!)that has a tendancy to become corrupt and too big. To resolve the problem, keep your lease times short (12 hours,etc). You may also have to periodically manually release leases to clean up the db.
