Although Windows Server 2003 has been with us a while I can across this issue recently. This only because most of the 2003 domain controller installations I had seen were 32bit. But recently I found a domain that had a mixture of 32bit and 64bit domain controllers.

You run netdiag on your Windows 2003 64bit domain controller and get many failures like the ones bellow:

DNS test . . . . . . . . . . . . . : Failed
[FATAL] Could not open file C:WINDOWSsystem32confignetlogon.dns for reading.
[FATAL] No DNS servers have the DNS records for this DC registered.

Redir and Browser test . . . . . . : Failed
List of NetBt transports currently bound to the Redir

DC list test . . . . . . . . . . . : Failed
Failed to enumerate DCs by using the browser. [ERROR_NO_BROWSER_SERVERS_FOUND]

Kerberos test. . . . . . . . . . . : Failed
[FATAL] Cannot lookup package Kerberos.
The error occurred was: (null)

Before you start diagnosing what the problem is check that netdiag that you are running is a correct version. It is very common that 32bit netdiag version is running on 64bit OS.

On the machine find netdiag.exe. If it is located in Program files(x86) folder then most likely it is the wrong version. Locate your Windows 2003 x64 installation CD browse to SUPPORTTOOLS open the support.cab file there you’ll find netdiag.exe. Extract and run it. All the errors that you’ve seen before should be gone.
There is no easy way to distinguish between 32bit and 64bit versions of netdiag. The file versions are the same the only difference is the size. 64bit version is ~100KB bigger. In my case 32bit version is 381KB and 64bit 489KB
Also on Microsoft Download Center you can only download Windows Server 2003 Service Pack 2 32-bit Support Tools and although it states that it runs on Windows Server 2003 x64, the version of netdiag.exe included is 32bit.