136.90.129.82.flex.network has no CNAME records.
Question and response
Question
dig 136.90.129.82.flex.network. NS
Answer
The response has no answer records.
Authority
flex.network. 1283 SOA ns1.flexnetwork.fr. noc.flexnetwork.fr. 2025011501 10800 3600 604800 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0