2008 R2 DCDIAG errors with NIC teaming

I’m in the process of deploying a couple new Server 2008 R2 domain controllers. I’m using two IBM blades, each having a pair of Broadcom NICs that I configured in fault-tolerance teams.

In trying to verify the configuration of one of the DCs, I used the command:

dcdiag /test:dns

The output surprised me:

Starting test: Connectivity 
    Message 0x621 not found. 
    Got error while checking LDAP and RPC connectivity. Please check your firewall settings. 
    ......................... CDC01 failed test Connectivity

I ran the command from a Server 2008 Sp2 (not R2) host:

dcdiag /s:cdc01 /test:dns

The test passed without error. Strange. I verified firewall and DNS. Then turned to the hivemind. This post shows similar behavior. This post on the TechNet forums identified the NIC Team as a probable source, and a contributor referenced a hotfix KB978387 for a bug in dcdiag on Server 2008 R2 on systems with NIC Teams.

Installed and now the test passes:

Starting test: Connectivity
   ......................... CDC01 passed test Connectivity

I spent much of my day working on this, and on tracking the connections to AD by clients using unsigned SASL binds or LDAP simple binds without an encrypted connection.

1 thought on “2008 R2 DCDIAG errors with NIC teaming

  1. srehfuss

    Thanks Geoff. I spent a long time trying to figure out the same problem. My VM 2008 R2 domain controllers were perfectly fine when joining my native 2003 domain but the hardware (HP DL360 G6 w/ dual GB Broadcom nics) server I am setting up with teamed NICs got the same RPC Connectivity error. This post saved me a lot of time. Thank you again.

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.