Apex domains cannot have CNAME records.
Question and response
Question
dig data2.web.az. NS
Answer
data2.web.az. 5 NS ns3.host.az.
data2.web.az. 5 NS ns1.host.az.
data2.web.az. 5 NS ns2.host.az.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0