Apex domains cannot have CNAME records.
Question and response
Question
dig 177.in-addr.arpa. NS
Answer
177.in-addr.arpa. 5 NS a.lactld.org.
177.in-addr.arpa. 5 NS ns2.lacnic.net.
177.in-addr.arpa. 5 NS rirns.arin.net.
177.in-addr.arpa. 5 NS ns.lacnic.net.
177.in-addr.arpa. 5 NS a.arpa.dns.br.
177.in-addr.arpa. 5 NS ns3.afrinic.net.
177.in-addr.arpa. 5 NS ns4.apnic.net.
177.in-addr.arpa. 5 NS ns4.lacnic.net.
177.in-addr.arpa. 5 NS lacnic.authdns.ripe.net.
Authority
The response has no authority records.
Additional
a.lactld.org. 5 A 200.0.68.10
ns.lacnic.net. 5 A 200.3.13.10
ns2.lacnic.net. 5 A 200.3.13.11
ns3.afrinic.net. 5 A 204.61.216.100
ns4.apnic.net. 5 A 202.12.31.53
ns4.lacnic.net. 5 A 190.112.52.35
a.lactld.org. 5 AAAA 2801:14:a000:0:0:0:0:10
ns.lacnic.net. 5 AAAA 2001:13c7:7002:3000:0:0:0:10
ns2.lacnic.net. 5 AAAA 2001:13c7:7002:3000:0:0:0:11
ns3.afrinic.net. 5 AAAA 2001:500:14:6100:ad:0:0:1
ns4.apnic.net. 5 AAAA 2001:dd8:12:0:0:0:0:53
ns4.lacnic.net. 5 AAAA 2001:13c7:7020:210:0:0:0:35
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0