mail.brilliantnavigator.com has no CNAME records.
Question and response
Question
dig mail.brilliantnavigator.com. NS
Answer
The response has no answer records.
Authority
brilliantnavigator.com. 3600 SOA ns1.loopia.se. registry.loopia.se. 1772668800 14400 3600 604800 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0