Apex domains cannot have CNAME records.
Question and response
Question
dig nstld.com. NS
Answer
nstld.com. 2 NS av4.nstld.com.
nstld.com. 2 NS av1.nstld.com.
nstld.com. 2 NS av2.nstld.com.
nstld.com. 2 NS av3.nstld.com.
Authority
The response has no authority records.
Additional
av1.nstld.com. 2 A 192.42.177.30
av2.nstld.com. 2 A 192.42.178.30
av3.nstld.com. 2 A 192.82.133.30
av4.nstld.com. 2 A 192.82.134.30
av1.nstld.com. 2 AAAA 2001:500:124:0:0:0:0:30
av2.nstld.com. 2 AAAA 2001:500:125:0:0:0:0:30
av3.nstld.com. 2 AAAA 2001:500:126:0:0:0:0:30
av4.nstld.com. 2 AAAA 2001:500:127:0:0:0:0:30
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0