gw.bul.net has no CNAME records.
Question and response
Question
dig gw.bul.net. NS
Answer
The response has no answer records.
Authority
bul.net. 3600 SOA bsh1.bul.net. noc.bul.net. 2024010779 10800 3600 604800 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0