vmi2720656.contaboserver.net has no CNAME records.
Question and response
Question
dig vmi2720656.contaboserver.net. NS
Answer
The response has no answer records.
Authority
contaboserver.net. 1436 SOA ns1.contabo.net. hostmaster.contabo.de. 1771729288 10800 3600 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0