Apex domains cannot have CNAME records.
Question and response
Question
dig mapfre.com. NS
Answer
mapfre.com. 2 NS esdns1.mapfre.com.
mapfre.com. 2 NS esdns3.mapfre.com.
mapfre.com. 2 NS esdns2.mapfre.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0