No federation for additional SIP domains

The other day I had a call from a customer for which I quite recently set up Lync Server 2010. They were experiencing problems for some of their employees not being able to federate with external domains.

The customer was housing a few domains besides their own, and the server was set up to support this:

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Dynamic federation was already set up, and the IT tech I was talking to had no problems federating.

Looking into the error messages using snooper, the error soon stood out pretty clear:

The “No match for domain in DNS SRV results” is actually one of the more specific ones MSFT has thrown me like…ever.

Using nslookup I could quite easily confirm that the customer had not set up external DNS the way I had told them to.

Instead of having a SRV record _sipfederationtls._tcp.<domain>.no point to an A record sip.<domain>.no using the same domain in both, they had rather pointed the SRV record to the main SIP domain A record, causing a domain redirect in the lookup. Lync is not fond of such things, and therein lay the broken federation.


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