ns4.a2hosting.com has no CNAME records.
Question and response
Question
dig ns4.a2hosting.com. NS
Answer
The response has no answer records.
Authority
a2hosting.com. 1428 SOA cass.ns.cloudflare.com. dns.cloudflare.com. 2397690148 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0