vps1.slaskdatacenter.com has no CNAME records.
Question and response
Question
dig vps1.slaskdatacenter.com. NS
Answer
The response has no answer records.
Authority
slaskdatacenter.com. 2989 SOA ns1.slaskdatacenter.com. hostmaster.slaskdatacenter.com. 2022091502 3600 3600 1209600 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0