Monitors

A monitor issues health checks at regular intervals to evaluate the health of each server within an origin pool.

When a pool becomes unhealthy, your load balancer takes that pool out of the server rotation.

Health checks that result in a status change for an origin server are recorded as events in the Load Balancing event logs.

​​ Properties

For an up-to-date list of monitor properties, refer to Monitor properties in our API documentation.

​​ Create monitors

For step-by-step guidance, refer to Create monitors.

​​ Health check regions

When you attach a monitor to a pool, you can select multiple regions to increase reporting accuracy.

For each option selected in a pool’s Health Check Regions, Cloudflare sends health checks from three separate data centers in that region.

If the majority of data centers for that region pass the health checks, that region is considered healthy. If the majority of regions is healthy, then the origin itself will be considered healthy.

​​ Configurations

All Data Centers (Enterprise only)

Health check probes are sent from every single data center in Cloudflare’s network to the origins within the associated pool. This allows probes to hit each origin during intervals set by the customer.

All Regions

Three health check probes per region are sent to each origin in the associated pool. There are a total of 13 regions, resulting in 39 probes.

Regional

Three health check probes are sent from each specified region within the pool configuration.

​​ Host header prioritization

When a load balancer runs health checks, headers set on an origin override headers set on a monitor. For more details, refer to Override HTTP Host headers.

​​ API commands

The Cloudflare API supports the following commands for monitors. Examples are given for user-level endpoint but apply to the account-level endpoint as well.