ns3.contabo.net has no CNAME records.
Question and response
Question
dig ns3.contabo.net. NS
Answer
The response has no answer records.
Authority
contabo.net. 1329 SOA ns1.contabo.net. hostmaster.contabo.de. 1771733216 10800 3600 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0