How to Use Load Balancers with

The job of a load balancer is to distribute traffic across a cluster of servers with the goal of reducing the chances that a single point will fail. In practice, these networks increase responsiveness and improve application availability. 

Load balance is an important function of network security, and a critical layer of infrastructure that many mid-sized and larger websites have adopted in recent years. 

To ensure that tracks accurate downtime for your website, you must also take into account any load balancing that may be in effect.

Table of Contents

Set the Proper Minimum Checks


Your network infrastructure may have multiple layers to help distribute traffic, preserve availability, and/or protect from DDoS. There are three types of load balancers: 

  • Hardware
  • Software
  • Cloud-based

In the average load balance scenario, you might consider a check for the layer of load balance infrastructure as well as one for the IP/URL of your site/application. 

Monitoring a Load Balancer Accessible via Public IP


In general, we recommend not only checking the load balancer but also the servers sitting behind it with direct traffic. 

First, configure a check to monitor your load balancer if it is reachable from a public IP address or DNS host name. We also suggest using an HTTP(S) check configured directly to the web server’s origin IP address or DNS host name, not the load balancer IP address or host name.


Tell to go directly to the server origin IP address that hosts the application/domain

Specify a Host HTTP header as shown below:


Override the Header with “Host” to distinguish between the origin IP

Should I Whitelist


Every situation is unique. 

If your server has an IP or DNS that is not accessible publicly, we sometimes suggest whitelisting the specific probe servers your check is using. Whitelisting also applies to firewalls and WAFs

A full list of our probe servers may be found under Support> Probe Servers. Select the probe server IPs that apply to the locations you monitor from to whitelist with your internal servers. Once complete, our probe servers will have access and can monitor freely.  

You can also add additional checks configured to monitor from these probe server locations, and whitelisting should apply to each subsequent check.

Additionally, we suggest that you subscribe to our Status Page for up-to-the-minute alerts of our server IP’s. 

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