Alibaba Cloud DNS:HTTP(S) health check

Parameters

1. Health check protocol

   Select HTTP(S) to monitor target IP addresses for web server network reachability, service availability, and first-packet latency.

2. Health check interval

   Interval between health checks. Default: 1 minute. Ultimate Edition supports a minimum of 15 seconds.

3. Health check port

   Port that receives health check requests. Default: 80 (HTTP) or 443 (HTTPS). Custom ports are supported.

4. Timeout

   Maximum wait time for a health check response. If no response is received within the timeout, the check fails. Valid values: 2, 3, 5, or 10 seconds.

5. Unhealthy threshold

   Number of consecutive failures required before an application service is marked unhealthy. Helps prevent false alarms from transient network issues. Valid values: 1, 2, or 3.

   • 1: Mark unhealthy after one failure.

   • 2: Mark unhealthy after two consecutive failures.

   • 3: Mark unhealthy after three consecutive failures.

6. Failure rate

   Percentage of monitoring nodes that must report a failure before an application service is marked unhealthy. Valid values: 20%, 50%, 80%, or 100%.

7. Failure return code

   HTTP status code threshold that indicates a failed health check. The service is marked unhealthy if the response code meets or exceeds this value.

   • 400 or higher: Client errors (bad requests, invalid parameters). If you select this threshold, you must specify the exact access path in the URL path field.

   • 500 or higher (default): Server errors indicating internal failures.

8. Host header

   Value of the Host header in health check requests. Identifies the target website. Defaults to the service domain name from your global configuration.

9. URL path

   The path for the HTTP(S) health check request. The default value is /.

10. Enable SNI

    If enabled, sends the server name during TLS negotiation for SNI support.

11. Follow 3xx redirection

    If enabled, the health check follows redirects when it receives a 3xx status code, such as 301, 302, 303, 307, or 308.

12. Monitoring nodes

    Geographic locations of the nodes that perform health checks. Default monitoring nodes:

    Node type	Geographic location
    BGP nodes	Zhangjiakou, Qingdao, Hangzhou, Shanghai, Hohhot, Shenzhen, Beijing
    International nodes	China (Hong Kong), Germany, Singapore, California, Malaysia, Japan
    Carrier nodes	Wuhan Unicom, Dalian Unicom, Nanjing Unicom, Tianjin Unicom, Qingdao Telecom, Changsha Telecom, Xi'an Telecom, Zhengzhou Telecom, Shenzhen Mobile, Dalian Mobile, Nanjing Mobile

    Important

    If all IP addresses in the address pool belong to Alibaba Cloud and you use a blackhole filtering policy for failure detection, select carrier nodes. Blackhole filtering is an ACL that takes effect at the border between Alibaba Cloud and public carriers. Traffic between Alibaba Cloud IP addresses stays within the internal network, which reduces the effectiveness of probes from other Alibaba Cloud nodes.

Procedure

1. Log on to the Alibaba Cloud DNS - Global Traffic Manager console.

2. On the instance list page, find the target instance and click Actions in the Configure column.

• To configure a new instance, follow the Tutorials.

• For instances configured with quick setup, go to Address Pool Configuration > click + to expand an address pool > Health Check > Modify.