f.ext.nic.fr has no CNAME records.
Question and response
Question
dig f.ext.nic.fr. NS
Answer
The response has no answer records.
Authority
nic.fr. 2532 SOA dnsmaster.nic.fr. hostmaster.nic.fr. 2026022801 7200 1800 2419200 5400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0