Health check

View, create, and manage your health check configurations.

In Global Server Load Balance (GSLB) deployments, health checks are used to poll virtual servers to determine their availability. A health check profile can include results from multiple checks. For example, you can configure an HTTP health check test and a TCP health check test.

• Before you begin

• Configure health check

• Add Health Check to a Virtual Server

Predefined health check configuration objects

Predefined health check configuration objects are available to help you get started. These can be used as-is or serve as templates for creating custom health check objects.

Predefined	Description
Default_HLTHCK_HTTP	Sends a HEAD request to the server port 80. Expects the server to return an HTTP 200.
Default_HLTHCK_HTTPS	Sends a HEAD request to the server port 443. Expects the server to return an HTTP 200.
Default_HLTHCK_ICMP	Pings the server.
Default_HLTHCK_TCP_ECHO	Sends a TCP echo to server port 7. Expects the server to respond with the corresponding TCP echo.

Before you begin

• You should have a solid understanding of TCP/IP and global load balancing concepts.

  • You must know the IP address, port, and configuration details of the local load balancing servers.

• For certain protocol checks, valid user credentials are required.

  • You must have Read-Write permission for Load Balance settings.

• Health checks will be performed from the following IP addresses. To avoid disruptions caused by misidentification as DDoS attacks, please add the following IPs to your application's allowlist:

  • USA: 44.231.37.61

  • Europe: 18.195.172.168 (new)

  • Asia Pacific: 52.77.144.83 (new)

Configure health check

1. Go to Health Check, click Create New to display the configuration editor.
2. Select one of the following options:

• ICMP
• TCP Echo
• TCP
• HTTP
• HTTPS
• UDP
• DNS

Complete the configuration as described in Health check configuration.

Save the configuration.

Setting	Guidelines
Name	Configuration name. Valid characters are A-Z, a-z, 0-9, _, and -. No spaces. After you initially save the configuration, you cannot edit the name.
Type	Select a type of health check.
General
Destination Address Type	IPv4
IPv4 Address	The IPv4 address to send health check traffic. If you do not specify an IPv4 address, the virtual server IPv4 address is used.
Interval	Seconds between each health check. Should be more than the timeout to prevent overlapping health checks. The default is 30.
Timeout	Seconds to wait for a reply before assuming that the health check has failed. The default is 10.
Area	Select the geographical areas(s) where the health check will be performed.
Healthy Area Threshold	Specifies the number of areas that must be healthy for the health check to be considered a pass.
Up Retry	Attempts to retry the health check to see if a down server has become available. The default is 1.
Down Retry	Attempts to retry the health check to see if an up server has become unavailable. The default is 3.
Specifics
TCP / UDP
Port	Listening port number of the virtual server.
HTTP / HTTPS
Port	Listening port number of the virtual server. Usually HTTP is 80, HTTPS is 443. If testing an HTTP proxy server, specify the proxy port.
SSL Ciphers	For HTTPS only. Default selections are recommended.
Local Cert	For HTTPS only. Paste the local SSL Health Check Client certificate into the blank.
HTTP CONNECT	Specify an HTTP CONNECT option: Local CONNECT—Use HTTP CONNECT to test the tunnel connection through the proxy to the remote server. The virtual server is deemed available if the request returns status code 200 (OK). Remote CONNECT—Use HTTP CONNECT to test both the proxy server response and remote server application availability. If you select this option, you can configure an HTTP request within the tunnel. For example, you can configure an HTTP GET/HEAD request to the specified URL and the expected response. No CONNECT—Do not use the HTTP CONNECT method. This option is the default. The HTTP CONNECT option is useful to test the availability of proxy servers only.
Remote Host	If you use HTTP CONNECT to test proxy servers, specify the remote server IP address.
Remote Port	If you use HTTP CONNECT to test proxy servers, specify the remote server port.
Method Type	HTTP method for the test traffic: HTTP GET—Send an HTTP GET request to the server. A response to an HTTP GET request includes HTTP headers and HTTP body. HTTP HEAD—Send an HTTP HEAD request. A response to an HTTP HEAD request includes HTTP headers only.
Send String	The request URL, such as /contact.php.
Receive String	A string expected in return when the HTTP GET request is successful.
Status Code	The health check sends an HTTP request to the server. Specify the HTTP status code in the server reply that indicates a successful test. Typically, you use status code 200 (OK). Other status codes indicate errors.
Match Type	What determines a failed health check? Match String Match Status Match All (match both string and status) Not applicable when using HTTP HEAD. HTTP HEAD requests test status code only.
DNS
Domain Name	The FQDN, such as www.example.com, to use in the DNS A/AAAA record health check.
Address Type	IPv4
Host Address	IP address that matches the FQDN, indicating a successful health check.

Add Health Check to a Virtual Server

There are two methods to add health checks to virtual servers:

Add Health Check to Virtual Server via Topology Page

1. Navigate to GSLB >Topology.

2. Right-click the virtual server and select Edit. This opens the Edit Virtual Server side panel.

   

3. Enable Health Check, then select the Health Check Relationship and applicable health checks from the Health Check list.

   Health Check Relationship:

   • AND — All of the specified health checks must pass for the virtual server to be considered available.

   • OR — One of the specified health checks must pass for the virtual server to be considered available.

Add Health Check to Virtual Server via Fabric Connector page

1. Navigate to GSLB > Virtual Server > Fabric Connector.

2. Click the three-dot menu on the connector card and select Manage Virtual Server. This opens the Edit Virtual Server side panel.

   

3. 1. Enable Health Check, then select the Health Check Relationship and applicable health checks from the Health Check list.

      Health Check Relationship:

      • AND — All of the specified health checks must pass for the virtual server to be considered available.

      • OR — One of the specified health checks must pass for the virtual server to be considered available.