Apex domains cannot have CNAME records.
Question and response
Question
dig server.lineasdns.com. NS
Answer
server.lineasdns.com. 5 NS ns1.lineasdns.com.
server.lineasdns.com. 5 NS ns2.lineasdns.com.
Authority
The response has no authority records.
Additional
ns1.lineasdns.com. 5 A 199.58.86.67
ns2.lineasdns.com. 5 A 199.58.86.68
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0