Server Fault is a question and answer site for system and network administrators. It's 100% free, no registration required.

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I am running SBS 2011, with all updates applied.

I get the following error EventID 1008 Unable to register the MSExchangeAB RPC interface. Failed with the error code The endpoint is a duplicate (1740).

Netstat dump with processes below:

  TCP               LISTENING       7056
Microsoft.Exchange.RpcCli     7056 MSExchangeRPC

  TCP               LISTENING       4148
spnsrvnt.exe                  4148 SentinelProtectionServer

  TCP               LISTENING       568
lsass.exe                      568 kdc, Netlogon, NTDS, SamSs

I have seen other posts that say this is to do with Global Catalog, however it is a DC as it is Small Business Server and therefore must already be a GC.

What could I start checking to resolve this?

share|improve this question
What's the event id in the application event log for this? As well the source. Are you sure you have "RPC over HTTP" installed? – Vick Vega Aug 26 '12 at 23:54

Good to know that you resolved this issue yourself.

With MSExchange/SBS/Windows Server you need to watch and ensure that ports 6001-6005 are not being used by any other apps. Apart from AB, there are other RPC services also which use these ports.

share|improve this answer
up vote 0 down vote accepted

This happened to be the SentinelProtectionServer from the Avaya IP Office Manager application, it was running and talking over the port that the Offline Address Book service normally runs on.

The Avaya IP Office Manager Application was removed, server rebooted, and the Offline Address Book service was able to start.

share|improve this answer
Thank you g18c, also in mu case it was the sentinel protection services. But i just stopped both the sentinel services, started the Exchange AB service, and restarted the sentinel services. Now all the services are running fine. I think that the problem occurs only if the sentinel protection services start before the Exchange AB service... Thanks anyway you drive me to the solution Regards Luca – Luca Mar 30 at 12:51

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.