Apex domains cannot have CNAME records.
Question and response
Question
dig static.netvigator.com. NS
Answer
static.netvigator.com. 5 NS ns4.netvigator.com.
static.netvigator.com. 5 NS ns5.netvigator.com.
Authority
The response has no authority records.
Additional
ns4.netvigator.com. 5 A 203.198.7.66
ns5.netvigator.com. 5 A 218.102.23.229
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0