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Load Balancing
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A monitor issues health monitor requests 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 monitor requests 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 monitor 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 Monitor Regions, Cloudflare sends health monitor requests from three separate data centers in that region.

Health monitor requests come from three data centers within each selected region.

If the majority of data centers for that region pass the health monitor requests, 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 monitor 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 monitor probes per region are sent to each origin in the associated pool. There are a total of 13 regions, resulting in 39 probes.


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

​​ Host header prioritization

When a load balancer runs health monitor requests, 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.

Create MonitorPOSTaccounts/:account_id/load_balancers/monitors
Delete MonitorDELETEaccounts/:account_id/load_balancers/monitors/:id
List MonitorsGETaccounts/:account_id/load_balancers/monitors
Monitor DetailsGETaccounts/:account_id/load_balancers/monitors/:id
Overwrite specific propertiesPATCHaccounts/:account_id/load_balancers/monitors/:id
Overwrite existing monitorPUTaccounts/:account_id/load_balancers/monitors/:id
Preview MonitorPOSTaccounts/:account_id/load_balancers/monitors/:id/preview

​​ Supported protocols

Cloudflare Load Balancing supports public monitoring for HTTP, HTTPS, TCP, UDP, ICMP, ICMP ping, and SMTP.

Load Balancing also supports private monitoring for HTTP, HTTPS, and TCP.