mail.webcominc.com has no CNAME records.
Question and response
Question
dig mail.webcominc.com. NS
Answer
The response has no answer records.
Authority
webcominc.com. 4231 SOA pdns1.ultradns.net. awong.calliduscloud.com. 2014122245 86400 86400 86400 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0