Apex domains cannot have CNAME records.
Question and response
Question
dig atwab.ca. NS
Answer
atwab.ca. 5 NS aurora.atwab.io.
atwab.ca. 5 NS zenith.atwab.io.
atwab.ca. 5 NS compass.atwab.io.
atwab.ca. 5 NS polaris.atwab.io.
Authority
The response has no authority records.
Additional
aurora.atwab.io. 5 A 192.40.30.160
compass.atwab.io. 5 A 192.40.30.145
polaris.atwab.io. 5 A 192.40.30.135
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0