HTTP Error codes

here are some of the HTTP Error codes that can help u in log analysis

Information codes

100 - The request was successful. The process can now continue.
101 - The request for the server to switch protocols was accepted, such as a switch from ftp to http.

Success Codes

200 Info OK
201 Info Created
202 Info Accepted
203 Info Non-Authoritative Information
204 Info No Content
205 Info Reset Content
206 Info Partial Content

Detailed Info

200 - The item requested of the server is available (keep in mind, available, not accepted or completed).
201 - A new address has been created through the use of form posting, perl, cgi, etc..
202 - The request has been accepted (keep in mind that the request has been accepted, not completed).
203 - The information received is not from the server that the information was requested from, but from another source.
204 - There was no content to be given for the request. For instance if you click on a hyperlink, imagemap, or button that isn't linked to anything or doesn't do anything.
205 - A script has reset the displayed content.
206 - Only partial content has been displayed. This could be due to bandwidth, poor caching, bad html, or other reasons

Redirection codes

300 Info Multiple Choices
301 Info Moved Permanently
302 Info Found
303 Info See Other
304 Info Not Modified
305 Info Use Proxy
307 Info Temporary Redirect

Detailed Info

300 - You will either get a choice of pages or an error message when this occurs. The address is actually pointing to two multiple files and/or locations.
301 - The requested page has been permanently moved. The server will automatically redirect you to the new location.
302 - The requested page has been temporarily moved. The server will automatically redirect you to the new location.
303 - The requested data is stored in an alternate location and the GET method will be used to retrieve the data. If the actual error is returned then this may be due to a web server misconfiguration.
304 - The requested data has not been modified since the last request.
305 - The requested data may only be accessed via the use of a proxy server.
307 - The requested page has been moved. The server will automatically redirect you to the new location. Unlike Error 301 and 302 however, the server has not specified whether the move is temporary or permanent.

Client Error Codes

400 Info Bad Request
401 Info Unauthorized
402 Info Payment Required
403 Info Forbidden
404 Info Not Found
405 Info Method Not Allowed
406 Info Not Acceptable
407 Info Proxy Authentication Required
408 Info Request Timeout
409 Info Conflict
410 Info Gone
411 Info Length Required
412 Info Precondition Failed
413 Info Request Entity Too Large
414 Info Request-URI Too Large
415 Info Unsupported Media Type
416 Info Requested Range Not Satisfiable
417 Info Expectation Failed

Detailed Info

400 - The request was denied due to a syntax error in the request.
401 - Your IP address or the username/password you entered were not correct. Your request was denied as you have no permission to access the data.
402 - The data is not accessible at the time. The owner of the space has not yet payed their service provider.
403 - Your IP address or the username/password you entered were not correct. Your request was denied as you have no permission to access the data.
OR
The server was unable to serve the data that was requested.
404 - The document that has been requested either no longer exists, or has never existed on the server.
405 - The method you are using to access the document is not allowed. Possible methods include:
CONNECT,DELETE,GET,HEAD,OPTIONS,POST,PUT,TRACE.
406 - The client (webbrowser) does not accept the document format. The formats that may be specified not to accept are charset, encoding, certain file types, languages, or ranges.
407 - The browser has not been authenticated on the required proxy server to access the data. This error is probably most commonly returned by content filters/parental controls.
408 - The server has closed the socket due to communications between the client and server taking too long. This could be due to server load, bandwidth issues, the client being disconnected from the internet, etc.
409 - Too many requests for the same file at one time.
OR
There is a conflict with an established software rule. (ie: you are trying to copy over a file with an older version, or you do not have permissions to delete a file)
OR
This could be caused by a DNS issue.
410 - This is like a 404 error in that the document requested is not on the server, however this differs in that the server 'knows' that the file used to be there and 'believes' that the file may be back, so it returns 410 rather 404.
411 - When trying to send a document to the server the server did not recieve a Content-Length specification in the header.
412 - A precondition setting required by the client or server has not been met.
413 - The process is too large to process. (ie: a file you are trying to upload is too large to fit on the server, or a webpage you are trying to download is too large for the server to process)
414 - The URL requested is simply too long. It is most likely more than 1024, 2048, or 4096 characters in length.
415 - This usually occurs if the server does not support the type of media the client is requesting. (ie: the server does not support streaming media, but streaming media is on the server and the client is attempting to access it)
416 - The client request included a range for acceptable file size, however the document requested did not fit into that range.
417 - The client's expect header requested certain server behaviors that the server could not perform.

Server Error Codes

500 Info Internal Server Error
501 Info Not Implemented
502 Info Bad Gateway
503 Info Service Unavailable
504 Info Gateway Timeout
505 Info HTTP Version not supported

Detailed info

500 - The server encountered an error. This is most often caused by a scripting problem, a failed database access attempt, or other similar reasons.
501 - The method you are using to access the document can not be performed by the server. Possible methods include:
CONNECT,DELETE,GET,HEAD,OPTIONS,POST,PUT,TRACE.
502 - The document requested resides on a 3rd party server and the original server received an error from the 3rd party server.
503 - The server is overloaded or down for maintenance and due to this was unable to process the client request.
504 - Most likely the client has lost connectivity (disconnected from the internet) or the cleint's host is having technical difficulties. This could also mean that a server that allows access to the requested server is down, having bandwidth/load issues, or otherwise unavailable.
505 - The server does not support the HTTP version used by the client. (This usually occurs if the server is using an OLDER version of HTTP than the client.)