mx.subsys.no has no CNAME records.
Question and response
Question
dig mx.subsys.no. NS
Answer
The response has no answer records.
Authority
subsys.no. 34 SOA ns1.subsys.no. hostmaster.subsys.no. 1771043141 300 75 1209600 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0