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.

One 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.

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