spamfilter.axc.eu has no CNAME records.
Question and response
Question
dig spamfilter.axc.eu. NS
Answer
The response has no answer records.
Authority
axc.eu. 10800 SOA nszero1.axc.nl. hostmaster.axc.eu. 2017072740 14400 3600 1209600 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0