A critical part of an OCS deployment is SRV records for automatic sign in. It is critical that these are present and configured correct. An easy way to check them is using nslookup. Below are how to check SRV records and what SRV records need to be present.

1. Open cmd
2. Type: nslookup
3. Type: set type=all
4. Type the SRV record to list its content

For OCS 2007 R2

• External
  • _sip._tls.domain.com
    • Usually points to Access EDGE FQDN on port 443
  • _sipfederationtls._tcp.domain.com
    • Usually points to Access EDGE FQDN on port 5061
• Internal
  • _sipinternaltls._tcp.domain.com
    • Usually points to Pool name with correct sip domain on port 5061

For Exchange 2007/2010

• External autodiscover
  • _autodiscover._tcp.domain.com
    • Usually points to owa FQDN listener with NTLM negotiate on port 443