Unstable Server

In some scenarios, the web server responds with status codes when it is unable to handle the requests for reasons such as invalid requests, temporary overloading, or server maintenance. These errors are displayed with error codes, which define various scenarios of the errors. For example,

  • 502 Bad Gateway The server is acting as a gateway or proxy and received an invalid response from the upstream server.

  • 503 Service Unavailable The server is currently unavailable. The servers might be overloaded or down for maintenance.

  • 504 Gateway Time-out The server is acting as a gateway or proxy and did not receive a timely response from the upstream server.

These can be temporary conditions, but sometimes you have to implement a corrective measure on the webservers to make the webpages up and available.

Using the Unstable Server indicator, you can view these failures and take decisions about corrective actions to overcome the issues and ensure the client requests are served and the webpages are always available.

Select the Unstable server tab to view the issue details.

Unstable server

The Recommended Actions to troubleshoot the issue are:

  • Configure L7 monitors with appropriate parameters for the server that responds with 5xx errors. A monitor is an entity that tracks the service health. The appliance periodically probes the servers using the monitor bound to each service. If a server does not respond within a specified response timeout, and the specified probes fail, the service is marked DOWN. The appliance then performs load balancing among the remaining services. For more information to configure a monitor, see Custom Monitors

  • Troubleshoot the server

Under Details, you can view:

  • The time that occurred the unstable server anomaly

  • The service/service group name

  • Total occurrences

  • The anomaly severity such as high, low, and medium

  • The detection message indicating % of the responses from this service reporting 5xx errors

For detailed information on server error web transaction, see Web transaction analytics for server errors

Unstable Server

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