Apex domains cannot have CNAME records.
Question and response
Question
dig eurolines.eu. NS
Answer
eurolines.eu. 5 NS ns.cloudbear.eu.
eurolines.eu. 5 NS ns.cloudbear.nl.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0