ns2.dds.eu has no CNAME records.
Question and response
Question
dig ns2.dds.eu. NS
Answer
The response has no answer records.
Authority
dds.eu. 3507 SOA ns1.dds.nl. postmaster.dds.eu. 1 21600 3600 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0