mxscan.saix.net has no CNAME records.
Question and response
Question
dig mxscan.saix.net. NS
Answer
The response has no answer records.
Authority
saix.net. 3318 SOA igubu.saix.net. dnsadmin.saix.net. 2026013921 10800 3600 1209600 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0