_mailers.f6.security has no NS records.
NS records for this zone are defined at f6.security.
NS records for this zone are defined at f6.security.
Question and response
Question
dig _mailers.f6.security. NS
Answer
The response has no answer records.
Authority
f6.security. 60 SOA a.ns.selectel.ru. support.selectel.ru. 2026031811 10800 3600 604800 60
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0