We have an online lync account and one lync on premises account. We are trying to federate the two domains to enable chat and presence sharing between the two.
Online Lync client is ravish@ucfed.in and lync on premises client is ravishaggarwal@ggnucfederation.com. We have updated the SRV records for ggnucfederation.com as follows to enable federation with lync online.
_sipfederationtls._tcp.ggnucfederation.com --> sip.xmppspark.in
An A record for sip.xmppspark.in has also been added in the DNS to point to lync edge server. However we notice that, when we add ravishaggarwal@ggnucfederation.com from lync online, then no TLS handshake message is received at Lync edge server.
Interestingly, if we modify the SRV record to
_sipfederationtls._tcp.ggnucfederation.com --> sip.ggnucfederation.com
and correspondingly create A record for sip.ggnucfederation.com, then TLS handshake is initiated and done.
What could we have possibly missed that is causing problem in the first case? Is it necessary to create the SRV record of type sip.<domainname>?
As per my understanding, lync online should query the srv record to get the target machine for the sipfederationtls and accordingly initiate tls handshake with the host name specified in the srv record. Is there anything more to this?