mail.c2free.ru has no NS records.
NS records for this zone are defined at c2free.ru.
NS records for this zone are defined at c2free.ru.
Question and response
Question
dig mail.c2free.ru. NS
Answer
The response has no answer records.
Authority
c2free.ru. 1800 SOA camilo.ns.cloudflare.com. dns.cloudflare.com. 2393590619 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0