Apex domains cannot have CNAME records.
Question and response
Question
dig deserv.net. NS
Answer
deserv.net. 5 NS d1.ruweb.net.
deserv.net. 5 NS d2.ruweb.net.
Authority
The response has no authority records.
Additional
d1.ruweb.net. 5 A 46.254.23.52
d2.ruweb.net. 5 A 91.121.54.18
d1.ruweb.net. 5 AAAA 2a03:c980:beef:6002:46:254:23:52
d2.ruweb.net. 5 AAAA 2001:41d0:1008:2c3b:0:0:0:1
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0