Apex domains cannot have CNAME records.
Question and response
Question
dig bitly.com. NS
Answer
bitly.com. 5 NS ns-343.awsdns-42.com.
bitly.com. 5 NS ns-cloud-b1.googledomains.com.
bitly.com. 5 NS ns-1053.awsdns-03.org.
bitly.com. 5 NS ns-1689.awsdns-19.co.uk.
bitly.com. 5 NS ns-880.awsdns-46.net.
bitly.com. 5 NS ns-cloud-b2.googledomains.com.
bitly.com. 5 NS ns-cloud-b3.googledomains.com.
bitly.com. 5 NS ns-cloud-b4.googledomains.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0