Apex domains cannot have CNAME records.
Question and response
Question
dig comunitel.es. NS
Answer
comunitel.es. 5 NS ns1.abovedomains.com.
comunitel.es. 5 NS ns2.abovedomains.com.
Authority
The response has no authority records.
Additional
ns1.abovedomains.com. 5 A 103.224.182.9
ns1.abovedomains.com. 5 A 103.224.212.9
ns2.abovedomains.com. 5 A 103.224.182.10
ns2.abovedomains.com. 5 A 103.224.212.10
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0