Your network contains a SIP domain named contoso.com.
The network has a Lync Server 2010 infrastructure that contains an Edge pool.
You need to ensure that other Lync Server 2010 organizations on the Internet can automatically discover your Edge Servers for federation.
Which DNS records should you create?

A.
+ a Service Location (SRV) record named _sipextemat_tls.contoso.com
+ a Host (A) record named edge.contoso.com

B.
+ a Service Location (SRV) record named _sipextemaLtls.contoso.com
+ a Text (TXT) record named edge.contoso.com

C.
+ a Service Location (SRV) record named _sipfederationtIss_tcp.contoso.com
+ a Host (A) record named sip.contoso.com

D.
+ a Service Location (SRV) record named _sipfederationtls._udp.contoso.com
+ a Text (T)(T) record named sip.contoso.com

Explanation:
http://technet.microsoft.com/en-us/library/dd425138%28office.13%29.aspx

http://technet.microsoft.com/en-us/library/gg398201.aspx