Apex domains cannot have CNAME records.
Question and response
Question
dig mailix.mx. NS
Answer
mailix.mx. 5 NS pete.ns.cloudflare.com.
mailix.mx. 5 NS cruz.ns.cloudflare.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0