mx2.sendclean.net has no NS records.
NS records for this zone are defined at sendclean.net.
NS records for this zone are defined at sendclean.net.
Question and response
Question
dig mx2.sendclean.net. NS
Answer
The response has no answer records.
Authority
sendclean.net. 1800 SOA aryanna.ns.cloudflare.com. dns.cloudflare.com. 2396664284 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0