Apex domains cannot have CNAME records.
Question and response
Question
dig cruiseline.eu. NS
Answer
cruiseline.eu. 5 NS ns-500.awsdns-62.com.
cruiseline.eu. 5 NS ns-1709.awsdns-21.co.uk.
cruiseline.eu. 5 NS ns-1270.awsdns-30.org.
cruiseline.eu. 5 NS ns-1002.awsdns-61.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0