Apex domains cannot have CNAME records.
Question and response
Question
dig mapfre.net. NS
Answer
mapfre.net. 5 NS esdns1.mapfre.net.
mapfre.net. 5 NS esdns2.mapfre.net.
mapfre.net. 5 NS esdns3.mapfre.net.
Authority
The response has no authority records.
Additional
esdns1.mapfre.net. 5 A 195.53.217.13
esdns2.mapfre.net. 5 A 195.53.217.14
esdns3.mapfre.net. 5 A 195.235.248.4
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0