This happened when you have a public Cloud VPS. To fix this issue, just follow these steps:
1. Start, we need to set hostname
# hostname your_hostname
(it must be sub domain, for example ns1.domain.com)
2. edit /etc/sysconfig/network :
# nano /etc/sysconfig/network
change you hostname value accordingly
HOSTNAME=subdomain.yourdomain.com
3. Edit your hostss file
# nano /etc/hosts
127.0.0.1 subdomain.yourdomain.com
YOUR_SERVER_PUBLIC_IP subdomain.yourdomain.com
4. You need to add an A record to your sub domain, point to your server IP
5. Restart cwpsvr
# service cwpsrv restart