Apex domains cannot have CNAME records.
Question and response
Question
dig adobe.mx. NS
Answer
adobe.mx. 4 NS ns202.adobe.net.
adobe.mx. 4 NS ns204.adobe.net.
adobe.mx. 4 NS ns201.adobe.net.
adobe.mx. 4 NS ns205.adobe.net.
adobe.mx. 4 NS ns206.adobe.net.
adobe.mx. 4 NS ns203.adobe.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0