Apex domains cannot have CNAME records.
Question and response
Question
dig az.h5datacenters.com. NS
Answer
az.h5datacenters.com. 5 NS ns2.h5datacenters.com.
az.h5datacenters.com. 5 NS ns1.h5datacenters.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0