Apex domains cannot have CNAME records.
Question and response
Question
dig cdp.mil.do. NS
Answer
cdp.mil.do. 5 NS karina.ns.cloudflare.com.
cdp.mil.do. 5 NS lars.ns.cloudflare.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0