void.blackhole.mx has no CNAME records.
Question and response
Question
dig void.blackhole.mx. NS
Answer
The response has no answer records.
Authority
blackhole.mx. 10680 SOA a.ns14.net. postmaster.abusix.com. 2020081300 43200 7200 1209600 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0