_s46633477.fdmarc.net has no CNAME records.
Question and response
Question
dig _s46633477.fdmarc.net. NS
Answer
The response has no answer records.
Authority
fdmarc.net. 60 SOA ns1.fdmarc.net. hostmaster.fdmarc.net. 1 7200 900 1209600 60
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0