sk.vlasenko.net has no CNAME records.
Question and response
Question
dig sk.vlasenko.net. NS
Answer
The response has no answer records.
Authority
vlasenko.net. 300 SOA x.ns.joker.com. hostmaster.joker.com. 2026011086 14400 3600 1209600 300
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0