ns.datalink.bg has no CNAME records.
Question and response
Question
dig ns.datalink.bg. NS
Answer
The response has no answer records.
Authority
datalink.bg. 1782 SOA server.i-net.datalink.bg. admin.datalink.bg. 408 900 600 86400 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0