masterdns.np6.fr has no CNAME records.
Question and response
Question
dig masterdns.np6.fr. NS
Answer
The response has no answer records.
Authority
np6.fr. 1282 SOA level.np6.com. masterdns.np6.com. 2001111453 21600 3600 604800 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0