Apex domains cannot have CNAME records.
Question and response
Question
dig universityofcalifornia.edu. NS
Answer
universityofcalifornia.edu. 5 NS ns13e.ucop.edu.
universityofcalifornia.edu. 5 NS ns23e.ucop.edu.
Authority
The response has no authority records.
Additional
ns13e.ucop.edu. 5 A 128.48.102.75
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0