proof.rain.fr has no CNAME records.
Question and response
Question
dig proof.rain.fr. NS
Answer
The response has no answer records.
Authority
rain.fr. 3600 SOA dns1.equant.net. root.rain.fr. 2026010912 3600 600 2592000 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0