mx.terrahost.no has no CNAME records.
Question and response
Question
dig mx.terrahost.no. NS
Answer
The response has no answer records.
Authority
terrahost.no. 1289 SOA margo.ns.cloudflare.com. dns.cloudflare.com. 2397753892 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0