Event ID: 8250 troubleshoot exchange server

Event ID: 8250
Source: MSExchangeAL
Category: Service Control
Type: Error
The Win32 API call 'DsGetDCNameW' returned error code [0x54b] The
specified domain either does not exist or could not be contacted. The
service could not be initialized. Make sure that the operating system
was installed properly.

This is usually due to DNS problems.

1) Install the Windows 2000 Support Tools from the Windows 2000 CD-ROM.

2) On the Exchange server, from a command prompt:
NETDIAG /V > NETDIAG.TXT

3) On the Exchange server, from a command prompt:
DCDIAG /S:DC_SERVER_Name /V > DCDIAG.TXT

4) Review the output. You should see enough details to confirm whether this
is caused by DNS failures.

5) Be sure that you configure the Exchange server with ONLY local DNS
servers for your domain, not an ISP's DNS server as either the preferred or
secondary server.

Related articles:

Q262068 XADM: How to Set Up Exchange 2000
http://support.microsoft.com/defaul...b;EN-US;Q262068

Q264001 XADM: Exchange 2000 Setup Does Not Work Because of DNS settings
http://support.microsoft.com/defaul...b;EN-US;Q264001

Q292757 XADM: Exchange 2000 Setup and Installation Top Support Issues
http://support.microsoft.com/defaul...b;EN-US;Q292757

Also, you may want to verify that the Recipient Update Services (in the
Exchange System Manager, click Recipients > Recipient Update Services) are
configured with the correct information for Exchange and your Active
Directory Domain Controllers.

Just some thoughts...
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I had the exact problem
Cured it by:

Making sure that you can access GC (Global Catalog), try to access using domains and trust.

Making sure netlogon service and rpc service are running.

Restarted

Making sure the MS Exchange services are started up (the services started and Ex Manager had to manually start it).