Describe How to Deal with HTTP Error Codes F5N4 Practice Questions (Page 2)

Questions 6–10

1. 6foundation · easy

   Which NGINX log file is most useful for diagnosing the cause of a 500 Internal Server Error?

   • AThe access log
   • BThe audit log
   • CThe system log
   • DThe error log
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2. 7application · medium

   An NGINX reverse proxy is returning 502 Bad Gateway for requests to a WebSocket upstream. The error log shows: 'upstream prematurely closed connection while reading response header from upstream'. The WebSocket service is healthy and works when accessed directly. What is the most likely cause?

   • AThe proxy_http_version is set to 1.0, which does not support WebSocket upgrades. Set proxy_http_version to 1.1 and add the Upgrade and Connection headers.
   • BThe proxy_read_timeout is set too low, causing NGINX to close the connection. Increase the proxy_read_timeout value.
   • CThe upstream server is overloaded and dropping connections. Increase the upstream server's resources.
   • DThe client's browser does not support WebSocket. Ask the user to use a modern browser.
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4. 8application · medium

   Users are receiving 429 Too Many Requests errors from an NGINX server. The NGINX access log shows the 429 status for many requests from the same IP address. The application is not rate-limited at the application layer. What is the most likely cause?

   • AThe upstream server is returning 429 due to its own rate limiting. Increase the upstream's rate limit.
   • BThe client's IP is blocked by the firewall, returning 429. Adjust the firewall rules.
   • CThe limit_req directive is configured in NGINX, limiting requests per IP address. Adjust the limit_req_zone or increase the rate limit.
   • DThe server is overloaded, returning 429 to all requests. Increase server resources.
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5. 9foundation · easy

   A client receives a 504 Gateway Timeout error from NGINX. What does this error indicate?

   • AThe server encountered an internal configuration error.
   • BThe client is not authorized to access the resource.
   • CThe client's request was too large for the server to process.
   • DThe upstream server did not respond within the time allowed by NGINX.
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6. 10application · medium

   An NGINX server is returning intermittent 502 Bad Gateway errors. The error log shows: 'upstream prematurely closed connection while reading response header from upstream'. The upstream service is healthy and responds correctly when tested directly. What is the most likely cause?

   • AThe upstream server is overloaded and dropping connections. Increase the upstream server's resources.
   • BThe client's request is malformed, causing the upstream to close the connection. Fix the client application's request format.
   • CThe upstream service is closing the connection before sending a complete response, possibly due to a keepalive timeout. Adjust the upstream's keepalive settings or NGINX's proxy_http_version to 1.1.
   • DThe proxy_read_timeout is set too low, causing NGINX to close the connection. Increase the proxy_read_timeout value.
   Reveal Solution Discussion Select an answer first