mail.simlab.net has no CNAME records.
Question and response
Question
dig mail.simlab.net. NS
Answer
The response has no answer records.
Authority
simlab.net. 5741 SOA ns1.megapath.com. support.megapath.com. 1734984407 7200 300 604800 14400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0