post.secomtrust.net has no CNAME records.
Question and response
Question
dig post.secomtrust.net. NS
Answer
The response has no answer records.
Authority
secomtrust.net. 300 SOA ns01.secomtrust.net. root.secomtrust.net. 2026021800 1800 900 1209600 300
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0