Apex domains cannot have CNAME records.
Question and response
Question
dig tt. NS
Answer
tt. 5 NS a.lactld.org.
tt. 5 NS ripe.nic.tt.
tt. 5 NS pch.nic.tt.
Authority
The response has no authority records.
Additional
a.lactld.org. 5 A 200.0.68.10
pch.nic.tt. 172283 A 204.61.216.63
ripe.nic.tt. 170286 A 193.0.9.50
a.lactld.org. 5 AAAA 2801:14:a000:0:0:0:0:10
pch.nic.tt. 172283 AAAA 2001:500:14:6063:ad:0:0:1
ripe.nic.tt. 170286 AAAA 2a13:27c0:30:0:0:0:0:50
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0