Apex domains cannot have CNAME records.
Question and response
Question
dig trendmicro.eu. NS
Answer
trendmicro.eu. 5 NS usc4.akam.net.
trendmicro.eu. 5 NS ns1-72.akam.net.
trendmicro.eu. 5 NS aus1.akam.net.
trendmicro.eu. 5 NS eur5.akam.net.
trendmicro.eu. 5 NS ns1-155.akam.net.
trendmicro.eu. 5 NS eur2.akam.net.
trendmicro.eu. 5 NS use1.akam.net.
trendmicro.eu. 5 NS usw1.akam.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0