Nagios is a system that is used to determine if your server is running or not. If your server is unreachable, the Nagios system will send you an instant email warning.
The warning will look something like this:
***** Nagios *****
Notification Type: PROBLEM
Host: SERVER ID
CRITICAL - Plugin timed out after 10 seconds
Date/Time: Mon Jul 2 11:32:56 EDT 2012
If you receive one of these alerts, the first thing to do is to determine if your server is actually online or offline. If your server is offline, please open a ticket in your Customer Hub and one of our agents will respond to you within 15 minutes.
If your server is online you have received the message due to an error. The Nagios system uses a ping to determine if a server is up or down. To solve this problem, be sure to allow ping traffic through your firewall.
For Smart Servers with a Rapid Response or Level 5 package, please allow ping traffic from 18.104.22.168. For other Smart Servers, please allow traffic from 22.214.171.124/27.
For all types of Classic Servers, please allow ping traffic from 126.96.36.199 through your firewall.