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Response Codes

access_time Updated Sep 21, 2021

What is a “200” agent response code?

The Signal Sciences agent returns a “200” response code when a request is allowed through (similar to an HTTP 200 OK response).

What is a “406” agent response code?

By default, the Signal Sciences agent returns a “406” response code when a request is blocked (similar to an HTTP 406 NOT ACCEPTABLE response). You can configure rules to return alternative custom response codes other than 406 when a request is blocked.

What is a “499” agent response code?

A “499” response code indicates the client closed the connection mid-request.

What is an HTTP 504 response code?

A 504 response code is a timeout error which indicates that the gateway did not receive a response from the user’s upstream origin in the allotted time specified.

If a client is making a request and the Cloud WAF ALB does not receive the first header byte within 60 seconds of the TCP connection being established, the requesting client will receive a 504, while the SigSci Agent will respond with a 499. This means the requesting client, if making a longstanding request through a browser, will receive a 504 error in the browser, while the SigSci Console will show a 499 for the request.

Troubleshooting 504s correlated with 499s

The longstanding request will need to be optimized to meet the 60 second threshold. If the request cannot be optimized, reach out to our support team to explain the issue in detail and we will gladly help.

Relevant timeouts in the Cloud WAF architecture

  • The Cloud WAF agent has 60 seconds to start sending a response to the Application Load Balance (ALB)
  • The Cloud WAF agent has 10 seconds to negotiate TLS with the upstream
  • The Cloud WAF agent has 30 seconds to establish an HTTP connection to the upstream

What do “-2”, “-1”, or “0” agent response codes mean?

The -2, -1, and 0 response codes are error response codes that are applied to requests that weren’t processed correctly.

See the error response codes troubleshooting guide for additional information about these response codes.