Apex domains cannot have CNAME records.
Question and response
Question
dig ca.telus.com. NS
Answer
ca.telus.com. 2 NS pri2.dns.ca.telus.com.
ca.telus.com. 2 NS pri1.dns.ca.telus.com.
Authority
The response has no authority records.
Additional
pri1.dns.ca.telus.com. 2 A 154.11.136.2
pri2.dns.ca.telus.com. 2 A 154.11.145.2
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0