Apex domains cannot have CNAME records.
Question and response
Question
dig phishlabs.com. NS
Answer
phishlabs.com. 5 NS ns-1302.awsdns-34.org.
phishlabs.com. 5 NS ns-392.awsdns-49.com.
phishlabs.com. 5 NS ns-1000.awsdns-61.net.
phishlabs.com. 5 NS ns-1631.awsdns-11.co.uk.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0