Apex domains cannot have CNAME records.
Question and response
Question
dig thruinc.com. NS
Answer
thruinc.com. 5 NS a1.uberns.com.
thruinc.com. 5 NS b1.uberns.com.
Authority
The response has no authority records.
Additional
a1.uberns.com. 5 A 216.59.59.1
b1.uberns.com. 5 A 216.59.60.1
a1.uberns.com. 5 AAAA 2602:ffe2:53:0:0:0:0:1
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0