spf.spamcluster.nl has no CNAME records.
Question and response
Question
dig spf.spamcluster.nl. NS
Answer
The response has no answer records.
Authority
spamcluster.nl. 14 SOA intention.ns01.nl. hostmaster.intention.nl. 2026033331 3600 14400 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0