auth20.ns.wcom.com has no CNAME records.
Question and response
Question
dig auth20.ns.wcom.com. NS
Answer
The response has no answer records.
Authority
ns.wcom.com. 863 SOA omzdns9.verizon.com. hostmaster.mci.com. 1193 1920 960 604800 960
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0