Apex domains cannot have CNAME records.
Question and response
Question
dig np6.com. NS
Answer
np6.com. 5 NS masterdns.np6.com.
np6.com. 5 NS cafe.np6.com.
np6.com. 5 NS level.np6.com.
np6.com. 5 NS tequila.np6.com.
np6.com. 5 NS masterdns.np6.fr.
np6.com. 5 NS masterdns.np6.net.
Authority
The response has no authority records.
Additional
cafe.np6.com. 5 A 62.39.107.50
level.np6.com. 5 A 62.39.107.50
tequila.np6.com. 5 A 40.66.45.75
masterdns.np6.com. 5 A 62.39.107.50
masterdns.np6.net. 5 A 40.66.45.75
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0