foobar.grin.hu has no CNAME records.
Question and response
Question
dig foobar.grin.hu. NS
Answer
The response has no answer records.
Authority
grin.hu. 120 SOA ns0.grin.hu. grin.grin.hu. 1588970207 28800 7200 604800 120
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0