mail.premiumplastic.net has no CNAME records.
Question and response
Question
dig mail.premiumplastic.net. NS
Answer
The response has no answer records.
Authority
premiumplastic.net. 1936 SOA premiumplastic.net. postmaster.premiumplastic.net. 2025121601 10800 3600 604800 43200
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0