Apex domains cannot have CNAME records.
Question and response
Question
dig citelia.es. NS
Answer
citelia.es. 5 NS dns1.interdominios.com.
citelia.es. 5 NS dns2.interdominios.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0