mx.vhs.sk.eserver.net has no CNAME records.
Question and response
Question
dig mx.vhs.sk.eserver.net. NS
Answer
The response has no answer records.
Authority
sk.eserver.net. 1779 SOA ns1.eserver.net. hostmaster.eserver.sk. 2025102801 7200 3600 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0