querying sip SRV records

box:~ dude$ nslookup
> set q=srv
> _sip._udp.colab.sipfoundry.com
Server:  141.133.112.120
Address: 141.133.112.120#53

Non-authoritative answer:
*** Can't find _sip._udp.colab.sipfoundry.com: No answer

Authoritative answers can be found from:
_sip._udp.colab.sipfoundry.com
 origin = ns1.sedoparking.com
 mail addr = hostmaster.sedo.de
 serial = 2007021501
 refresh = 86400
 retry = 10800
 expire = 604800
 minimum = 86400
> 
> _sip._udp.sip.redhat.com
Server:  141.133.112.120
Address: 141.133.112.120#53

Non-authoritative answer:
_sip._udp.sip.redhat.com service = 3 0 5060 sipx-sbc03.geo.redhat.com.
_sip._udp.sip.redhat.com service = 4 0 5060 sipx-sbc04.geo.redhat.com.
_sip._udp.sip.redhat.com service = 1 0 5060 sipx-sbc01.geo.redhat.com.
_sip._udp.sip.redhat.com service = 1 0 5060 sipx-sbc02.geo.redhat.com.
_sip._udp.sip.redhat.com service = 2 0 5060 sipx-sbc03.geo.redhat.com.

Authoritative answers can be found from:
> _sip._udp.sbc.lafayette.edu
Server:  141.133.112.120
Address: 141.133.112.120#53

** server can't find _sip._udp.sbc.lafayette.edu: NXDOMAIN
> ^D 
box:~ dude$