Apex domains cannot have CNAME records.
Question and response
Question
dig thomascook.fr. NS
Answer
thomascook.fr. 5 NS nsusa.comlaude.net.
thomascook.fr. 5 NS nsgbr.comlaude.co.uk.
thomascook.fr. 5 NS nssui.comlaude.ch.
Authority
The response has no authority records.
Additional
nssui.comlaude.ch. 5 A 198.51.45.11
nsusa.comlaude.net. 5 A 198.51.44.75
nssui.comlaude.ch. 5 AAAA 2a00:edc0:6259:7:11:0:0:2
nsusa.comlaude.net. 5 AAAA 2620:4d:4000:6259:7:11:0:3
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0