Apex domains cannot have CNAME records.
Question and response
Question
dig 64.42.115.in-addr.arpa. NS
Answer
64.42.115.in-addr.arpa. 4 NS ns3.connect.net.pk.
64.42.115.in-addr.arpa. 4 NS dns.connect.net.pk.
64.42.115.in-addr.arpa. 4 NS ns1.connect.net.pk.
64.42.115.in-addr.arpa. 4 NS ns2.connect.net.pk.
Authority
The response has no authority records.
Additional
ns1.connect.net.PK. 4 A 118.103.239.9
ns2.connect.net.PK. 4 A 118.103.239.7
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0