filter.premiumantispam.nl has no CNAME records.
Question and response
Question
dig filter.premiumantispam.nl. NS
Answer
The response has no answer records.
Authority
premiumantispam.nl. 1338 SOA ns1.dn-s.nl. hostmaster.premiumantispam.nl. 2021010100 600 3600 1209600 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0