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Table Of Contents  The TCP/IP Guide
 9  TCP/IP Application Layer Protocols, Services and Applications (OSI Layers 5, 6 and 7)
      9  TCP/IP Key Applications and Application Protocols
           9  TCP/IP File and Message Transfer Applications and Protocols (FTP, TFTP, Electronic Mail, USENET, HTTP/WWW, Gopher)
                9  TCP/IP World Wide Web (WWW, "The Web") and the Hypertext Transfer Protocol (HTTP)
                     9  TCP/IP Hypertext Transfer Protocol (HTTP)
                          9  HTTP Messages, Message Formats, Methods and Status Codes

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HTTP Status Code Format, Status Codes and Reason Phrases
(Page 3 of 4)

Status Codes and Reason Phrases

Table 275 lists in numerical order the status codes defined by the HTTP/1.1 standard, along with the “standard” reason phrase and a brief description of each:


Table 275: HTTP Status Codes

Status Code

Reason Phrase

Description

100

Continue

Client should continue sending its request. This is a special status code; see below for details.

101

Switching Protocols

The client has used the Upgrade header to request the use of an alternative protocol and the server has agreed.

200

OK

Generic successful request message response. This is the code sent most often when a request is filled normally.

201

Created

The request was successful and resulted in a resource being created. This would be a typical response to a PUT method.

202

Accepted

The request was accepted by the server but has not yet been processed. This is an intentionally “non-commital” response that does not tell the client whether or not the request will be carried out; the client determines the eventual disposition of the request in some unspecified way. It is used only in special circumstances.

203

Non-Authoritative Information

The request was successful, but some of the information returned by the server came not from the original server associated with the resource but from a third party.

204

No Content

The request was successful, but the server has determined that it does not need to return to the client an entity body.

205

Reset Content

The request was successful; the server is telling the client that it should reset the document from which the request was generated so that a duplicate request is not sent. This code is intended for use with forms.

206

Partial Content

The server has successfully fulfilled a partial GET request. See the topic on methods for more details on this, as well as the description of the Range header.

300

Multiple Choices

The resource is represented in more than one way on the server. The server is returning information describing these representations, so the client can pick the most appropriate one, a process called agent-driven negotiation.

301

Moved Permanently

The resource requested has been moved to a new URL permanently. Any future requests for this resource should use the new URL.

This is the proper method of handling situations where a file on a server is renamed or moved to a new directory. Most people don't bother setting this up, which is why URLs “break” so often, resulting in 404 errors as discussed below.

302

Found

The resource requested is temporarily using a different URL. The client should continue to use the original URL. See code 307.

303

See Other

The response for the request can be found at a different URL, which the server specifies. The client must do a fresh GET on that URL to see the results of the prior request.

304

Not Modified

The client sent a conditional GET request, but the resource has not been modified since the specified date/time, so the server has not sent it.

305

Use Proxy

To access the requested resource, the client must use a proxy, whose URL is given by the server in its response.

306

(unused)

Defined in an earlier (draft?) version of HTTP and no longer used.

307

Temporary Redirect

The resource is temporarily located at a different URL than the one the client specified.

Note that 302 and 307 are basically the same status code. 307 was created to clear up some confusion related to 302 that occurred in earlier versions of HTTP (which I'd rather not get into!)

400

Bad Request

Server says, “huh?” J Generic response when the request cannot be understood or carried out due to a problem on the client's end.

401

Unauthorized

The client is not authorized to access the resource. Often returned if an attempt is made to access a resource protected by a password or some other means without the appropriate credentials.

402

Payment Required

This is reserved for future use. Its mere presence in the HTTP standard has caused a lot of people to scratch their chins and go “hmm…” J

403

Forbidden

The request has been disallowed by the server. This is a generic “no way” response that is not related to authorization. For example, if the maintainer of Web site blocks access to it from a particular client, any requests from that client will result in a 403 reply.

404

Not Found

The most common HTTP error message, returned when the server cannot locate the requested resource. Usually occurs due to either the server having moved/removed the resource, or the client giving an invalid URL (misspellings being the most common cause.)

405

Method Not Allowed

The requested method is not allowed for the specified resource. The response includes an Allow header that indicates what methods the server will permit.

406

Not Acceptable

The client sent a request that specifies limitations that the server cannot meet for the specified resource. This error may occur if an overly-restrictive list of conditions is placed into a request such that the server cannot return any part of the resource.

407

Proxy Authentication Required

Similar to 401, but the client must first authenticate itself with the proxy.

408

Request Timeout

The server was expecting the client to send a request within a particular time frame and the client didn't send it.

409

Conflict

The request could not be filled because of a conflict of some sort related to the resource. This most often occurs in response to a PUT method, such as if one user tries to PUT a resource that another user has open for editing, for example.

410

Gone

The resource is no longer available at the server, which does not know its new URL. This is a more specific version of the 404 code that is used only if the server knows that the resource was intentionally removed. It is seen rarely (if ever) compared to 404.

411

Length Required

The request requires a Content-Length header field and one was not included.

412

Precondition Failed

Indicates that the client specified a precondition in its request, such as the use of an If-Match header, which evaluated to a false value. This indicates that the condition was not satisfied so the request is not being filled. This is used by clients in special cases to ensure that they do not accidentally receive the wrong resource.

413

Request Entity Too Large

The server has refused to fulfill the request because the entity that the client is requesting is too large.

414

Request-URI Too Long

The server has refused to fulfill the request because the URL specified is longer than the server can process. This rarely occurs with properly-formed URLs but may be seen if clients try to send gibberish to the server.

415

Unsupported Media Type

The request cannot be processed because it contains an entity using a media type the server does not support.

416

Requested Range Not Satisfiable

The client included a Range header specifying a range of values that is not valid for the resource. An example might be requesting bytes 3,000 through 4,000 of a 2,400-byte file.

417

Expectation Failed

The request included an Expect header that could not be satisfied by the server.

500

Internal Server Error

Generic error message indicating that the request could not be fulfilled due to a server problem.

501

Not Implemented

The server does not know how to carry out the request, so it cannot satisfy it.

502

Bad Gateway

The server, while acting as a gateway or proxy, received an invalid response from another server it tried to access on the client's behalf.

503

Service Unavailable

The server is temporarily unable to fulfill the request for internal reasons. This is often returned when a server is overloaded or down for maintenance.

504

Gateway Timeout

The server, while acting as a gateway or proxy, timed out while waiting for a response from another server it tried to access on the client's behalf.

505

HTTP Version Not Supported

The request used a version of HTTP that the server does not understand.


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HTTP Message Headers
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