mail.datalink.bg has no NS records.
NS records for this zone are defined at datalink.bg.
NS records for this zone are defined at datalink.bg.
Question and response
Question
dig mail.datalink.bg. NS
Answer
The response has no answer records.
Authority
datalink.bg. 3600 SOA server.i-net.datalink.bg. admin.datalink.bg. 408 900 600 86400 3600
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0