conferencing.Level3.com has no CNAME records.
Question and response
Question
dig conferencing.Level3.com. NS
Answer
The response has no answer records.
Authority
Level3.com. 2162 SOA ns2.Level3.net. dns.level3.net. 2025102309 7200 600 2592000 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0