vmi742821.contaboserver.net has no CNAME records.
Question and response
Question
dig vmi742821.contaboserver.net. NS
Answer
The response has no answer records.
Authority
contaboserver.net. 2876 SOA ns1.contabo.net. hostmaster.contabo.de. 1771723784 10800 3600 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0