Apex domains cannot have CNAME records.
Question and response
Question
dig telus.com. NS
Answer
telus.com. 1 NS dns40.telus.com.
telus.com. 1 NS dns40.telus.ca.
Authority
The response has no authority records.
Additional
dns40.telus.ca. 1 A 209.171.204.40
dns40.telus.com. 1 A 209.171.203.40
dns40.telus.ca. 1 AAAA 2001:56b:d:8a00:0:0:0:40
dns40.telus.com. 1 AAAA 2001:56b:d:a00:0:0:0:40
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0