_prdgw.shellrent.com has no CNAME records.
Question and response
Question
dig _prdgw.shellrent.com. NS
Answer
The response has no answer records.
Authority
shellrent.com. 1392 SOA ada.ns.cloudflare.com. dns.cloudflare.com. 2397011409 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0