rirns.arin.net has no CNAME records.
Question and response
Question
dig rirns.arin.net. NS
Answer
The response has no answer records.
Authority
arin.net. 2396 SOA ns1.arin.net. bind.arin.net. 2021113330 10800 600 1209600 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0