0.b.4.1.0.0.a.2.ip6.arpa has no MX records.
Question and response
Question
dig 0.b.4.1.0.0.a.2.ip6.arpa. MX
Answer
The response has no answer records.
Authority
0.b.4.1.0.0.a.2.ip6.arpa. 86400 SOA p-dns.irz42.net. hostmaster.irz42.net. 2025051903 28800 7200 604800 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0