tencent cloud

Use Cases

Anti-DDoS Advanced health checks identify the running status of backend servers, where abnormal servers will be isolated to reduce the impact on overall business availability.

• Layer-4 health check
  The Anti-DDoS Advanced layer-4 health check mechanism is as follows: The Anti-DDoS cluster nodes initiate an access request to the server port specified and determine whether the port access is normal. If it is considered normal, the backend server is running properly, otherwise, the backend server is not functioning correctly.
  Under TCP protocol, the mechanism determines if the port is connected, while under UDP protocol, it determines whether the port is reachable with the ping command.
• Layer-7 health check
  The Anti-DDoS Advanced layer-7 health check mechanism is as follows: The Anti-DDoS cluster nodes initiate an HTTP request to the backend server specified and determine whether the backend server works properly according to HTTP response status codes.
  HTTP response status codes can be user-defined. Assume that http_1xx, http_2xx, http_3xx, http_4xx and http_5xx are returned. You can select http_1xx and http_2xx to indicate that the service is normal, while the unselected codes represent that the service is not working properly.

Note：

If only one real server IP is configured in a single forwarding rule, health checks will not be enabled. This feature is used when multiple real server IPs are configured.

Directions

Layer-4 health check configuration

1. Log in to the Anti-DDoS Advanced Console, select Anti-DDoS Advanced (New) > Application Accessing on the left sidebar, and then open the Access via ports tab.
2. Select an Anti-DDoS Advanced instance and rules before you click Edit.
   
3. On the page that pops up, click Show advanced options, set configuration items, and then click OK.

   Note：

   • By default, layer-4 health check is enabled. We recommend you use the default values when you configure this feature.
   • Under TCP protocol, the layer-4 health check determines if the port is connected, while under UDP protocol, it determines whether the port is reachable with the ping command.

Layer-7 health check configuration

1. Log in to the Anti-DDoS Advanced Console, select Anti-DDoS Advanced (New) > Application Accessing on the left sidebar, and then open the Access via ports tab.
2. Select an Anti-DDoS Advanced instance and rules before you click Configuration.
   
3. On the page that pops up, click Show advanced options, set configuration items, and then click OK.

   Note：

   By default, layer-7 health check is disabled.

Configuration Items

Layer-4 health check

Layer-7 health check