proxy.apptocloud.net has no CNAME records.
Question and response
Question
dig proxy.apptocloud.net. NS
Answer
The response has no answer records.
Authority
apptocloud.net. 2482 SOA dns1.ttc.cz.apptocloud.net. admin.apptocloud.net. 2026030601 10800 3600 777600 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0