fallback.denit.net has no CNAME records.
Question and response
Question
dig fallback.denit.net. NS
Answer
The response has no answer records.
Authority
denit.net. 3561 SOA ns1.masterdns.nl. hostmaster.denit.net. 2026012803 14400 3600 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0