website without www is 404

[adamhk0]

Please check the Vhost for that domain.

Also please confirm if that domain is using the sentora DNS (check that at domain registar).

I have CentOS 6 32bit. How to check vhost?

Yes, I am using Sentora DNS Manger. 
Sentora DNS Manger created nameservers (ns1.mydomain.com and ns2.mydomain.com).
At domain register, I have my domain nameservers set as ns1.mydomain.com and ns2.mydomain.com
And both nameservers (ns1.mydomain.com and ns2.mydomain.com) are pointed to my VPS ip.
Thank you.