What status code does a server typically return when an HTTP request times out?

HTTP protocol is a protocol used to transfer data between clients and servers. During the network communication process, sometimes the request initiated by the client cannot get a response from the server within the specified time, and a timeout occurs. When the HTTP request times out, the server will return a corresponding status code to inform the client of the specific reason for the request timeout. Below is a discussion of the status codes that the server may return when an HTTP request times out.

1. 408 Request Timeout
   When the server does not receive the client's request within the specified time, it will return status code 408. This usually means that the request initiated by the client took longer than the server allowed. Request timeouts can be caused by network latency, high server load, or the complexity of the request itself.
2. 504 Gateway Timeout
   When the client's request passes through a series of proxy servers and finally reaches the server, if there is no response from the server within the specified time, the server will return status code 504 . Gateway timeouts are usually caused by communication failures between proxy servers, internal server errors, or excessive server load.
3. 502 Gateway Error (Bad Gateway)
   Similar to status code 504, when the client's request reaches the server through the proxy server, if the proxy server gets a response from the server within the specified time, but the server returns If an error occurs in the response, status code 502 will be returned. Gateway errors are usually caused by communication failures between the proxy server and the backend server, internal server errors, or excessive server load.
4. 503 Service Unavailable
   When the server cannot handle the client's request due to maintenance, overload, or other reasons, status code 503 will be returned. This means that the server is temporarily unavailable and the client can try sending the request again later. The reasons why the service is unavailable may include that the server is undergoing update maintenance, the server load is too high, or the server encounters a failure.

To summarize, when an HTTP request times out, the server usually returns a status code such as 408, 504, 502, or 503 to indicate the specific reason for the request timeout. These status codes can help the client determine the cause of the request timeout and take appropriate measures, such as resending the request, reducing the server load, or waiting for the service to resume.

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