DNS Records in a Lync world (and their usage)
Automatic Sign-in Records (used by the Lync or Communicator client to locate a Lync or OCS server to sign-in)
  1.  _sipinternaltls._tcp.
  2.  _sipinternal._tcp.
  3.  _sip._tls.
  4.  _sip._tcp.
  5. sipinternal.
  6. sip.
  7. sipexternal.
Office 365 Sign-In Records (used by the Lync or Communicator client to locate the Lync Online server to sign-in)
  
  1. sip.
  2. _sip._tls.
  Lync Devices Records (used by Lync devices to locate a home registrar)
  1.   sipinternaltls._tcp.
  2.  _sipexternal._tls.
  3.  _sipexternaltls.
  4.  ucupdates-r2.
  5.  _ntp._udp.
 Lync Simple URL Records (used by Lync if DNS is the chosen simple URL configuration)
  1.  meet.example.com
  2.  dialin.example.com
  3.  admin.example.com
Federation (used by partners to automatically discover your Edge)
_sipfederationtls._tcp.
  Lync Mobility Auto-discovery Records (used by Lync mobile clients to auto-discover the Lync mobility service)
  1. Lyncdiscover.
  2. Lyncdiscoverinternal.
XMPP Auto-discovery Records
_xmpp-server._tcp..
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