mail2.sered.net has no NS records.
NS records for this zone are defined at sered.net.
NS records for this zone are defined at sered.net.
Question and response
Question
dig mail2.sered.net. NS
Answer
The response has no answer records.
Authority
sered.net. 1800 SOA fay.ns.cloudflare.com. dns.cloudflare.com. 2395345046 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0