mx.byet.net has no NS records.
NS records for this zone are defined at byet.net.
NS records for this zone are defined at byet.net.
Question and response
Question
dig mx.byet.net. NS
Answer
The response has no answer records.
Authority
byet.net. 1800 SOA johnathan.ns.cloudflare.com. dns.cloudflare.com. 2397355808 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0