ptr.133.19.16.81.static.yourvserver.net has no CNAME records.
Question and response
Question
dig ptr.133.19.16.81.static.yourvserver.net. NS
Answer
The response has no answer records.
Authority
yourvserver.net. 6932 SOA root-dns.netcup.net. dnsadmin.netcup.net. 2026010900 28800 7200 1209600 7200
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0