Apex domains cannot have CNAME records.
Question and response
Question
dig googledomains.com. NS
Answer
googledomains.com. 5 NS ns8.googledomains.com.
googledomains.com. 5 NS ns6.googledomains.com.
googledomains.com. 5 NS ns5.googledomains.com.
googledomains.com. 5 NS ns7.googledomains.com.
Authority
The response has no authority records.
Additional
ns5.googledomains.com. 5 A 216.239.32.10
ns6.googledomains.com. 5 A 216.239.34.10
ns7.googledomains.com. 5 A 216.239.36.10
ns8.googledomains.com. 5 A 216.239.38.10
ns5.googledomains.com. 5 AAAA 2001:4860:4802:32:0:0:0:a
ns6.googledomains.com. 5 AAAA 2001:4860:4802:34:0:0:0:a
ns7.googledomains.com. 5 AAAA 2001:4860:4802:36:0:0:0:a
ns8.googledomains.com. 5 AAAA 2001:4860:4802:38:0:0:0:a
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0