mailbox.octans.se has no CNAME records.
Question and response
Question
dig mailbox.octans.se. NS
Answer
The response has no answer records.
Authority
octans.se. 10800 SOA ns1.teknikbyran.com. registry.teknikbyran.com. 2023020723 28800 7200 1209600 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0