Webhook Health Check URL and Automatic Revalidation {#wh-fg-subscription-health-check-url}
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When you create a webhook subscription, `Cybersource` recommends that you include a health check URL in the request. Including a health check URL enables `Cybersource` to monitor your server's status for reliability. When `Cybersource` detects that your health check URL is unresponsive, notification deliveries are withheld until your health check URL becomes responsive again. A health check URL ensures that you do not miss any notifications.  
To add a health check URL to your *create a subscription* request, include the healthCheckurl field and set it to your health check URL. You must also include the deactivateflag field and set it to `true` to enable `Cybersource` to withhold notifications for periods when your server becomes unresponsive.

Automatic Activation
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After you successfully create or update a subscription, `Cybersource` pings your health check URL within five to ten minutes. If `Cybersource` receives a response, the subscription status automatically becomes `ACTIVE` and notifications are delivered. When `Cybersource` does not receive a response, your subscription status remains `SUSPENDED` until `Cybersource` receives a response. If you did not include a health check URL when you created the subscription, `Cybersource` pings your webhook URL for automatic activation instead. You can also activate a subscription that is not automatically activated by sending a PUT request. For more information, see [Activate a Webhook Subscription](/docs/cybs/en-us/webhooks/implementation/all/rest/webhooks/wh-fg-subscription-manage-intro/wh-fg-subscription-manage-activate-intro.md "").

#### Figure:

Webhook Automatic Activation ![](/content/dam/documentation/cybs/en-us/topics/payments-processing/payment-services/webhooks/images/webhooks-subscription-cybs-600x400.svg/jcr:content/renditions/original)

Automatic Revalidation
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After the subscription's initial activation, `Cybersource` continues to monitor your server status. If `Cybersource` detects that your server is unavailable, your subscription status automatically updates to `SUSPENDED`, and notifications are withheld. When `Cybersource` detects that your server is available again, your subscription status automatically updates to `ACTIVE`, and all withheld notifications are delivered.