mailfilter-in.wntpr.com has no CNAME records.
Question and response
Question
dig mailfilter-in.wntpr.com. NS
Answer
The response has no answer records.
Authority
wntpr.com. 6 SOA lennox.ns.cloudflare.com. dns.cloudflare.com. 2395610770 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0