Apex domains cannot have CNAME records.
Question and response
Question
dig 1-253.113.201.74.in-addr.arpa. NS
Answer
1-253.113.201.74.in-addr.arpa. 5 NS ns4.vtitan.com.
1-253.113.201.74.in-addr.arpa. 5 NS ns1.vtitan.com.
1-253.113.201.74.in-addr.arpa. 5 NS ns2.vtitan.com.
1-253.113.201.74.in-addr.arpa. 5 NS ns3.vtitan.com.
Authority
The response has no authority records.
Additional
ns1.vtitan.com. 5 A 165.173.187.13
ns2.vtitan.com. 5 A 117.20.43.94
ns3.vtitan.com. 5 A 121.244.91.40
ns4.vtitan.com. 5 A 122.15.156.168
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0