Apex domains cannot have CNAME records.
Question and response
Question
dig public.eastlink.ca. NS
Answer
public.eastlink.ca. 5 NS ns3.eastlink.ca.
public.eastlink.ca. 5 NS ns4.eastlink.ca.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0