mail.ultradnstools.com has no CNAME records.
Question and response
Question
dig mail.ultradnstools.com. NS
Answer
The response has no answer records.
Authority
ultradnstools.com. 10800 SOA pdns196.ultradns.com. domains.vercara.com. 2012101224 86400 86400 86400 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0