Website Design - Search Engine Optimization

Search Engine Optimization - SEO / SEM

Code		Meaning
500: Server errors
505	HTTP Version Not Supported	The server does not support the HTTP protocol version that was used in the request message. Should never happen with Robozilla; if it does, the server might be misconfigured.
504	Gateway Timeout	A server being used by this server has not responded in time.
503	Server Overload	Service temporarily overloaded. The server cannot process the request due to a high load.
502	Bad Gateway	The server, while acting as a gateway or proxy, received an invalid response from the upstream server it accessed in attempting to fulfill the request. Might be transient; hold for a few days and see if it clears up.
501	Not Implemented	Function not implemented in Web server software. Might occur when a site is moved to a different platform (operating system). Look for an updated URL.
500	Server error	Sometimes happens due to a server misconfiguration. Usually this is transient, and goes away, but check first.
400: Client errors
417	Expectation Failed	The expectation given in an Expect request-header field could not be met by this server. Should never happen to Robozilla.
416	Requested Range Not Satisfiable	A browser which sends information on acceptable file size as part of its request, has requested a file that does not fit these parameters. Since Robozilla does not send this header, this shouldn't happen unless the server is misconfigured.
415	Unsupported Media Type	The server is refusing to service the request because the entity of the request is in a format not supported by the requested resource for the requested method. Back up a few levels and see if there's an alternate version of the page you're looking for.
414	Request-URI Too Large	The URL (usually created by a GET form request) is too large for the server to handle. Check to see that a lot of garbage didn't somehow get pasted in after the URL.
413	Request Entity Too Large	The server is refusing to process a request because the request entity is larger than the server is willing or able to process. Should never occur for Robozilla.
412	Precondition Failed	The precondition given in one or more of the request-header fields evaluated to false when it was tested on the server. Should never occur for Robozilla.
411	Length Required	The server requires a content-length in the request. Should never occur for Robozilla.
410	Gone	The resource doesn't exist at all. The page was removed by the webmaster. This page should be deleted.
409	Conflict	The request could not be completed due to a conflict with the current state of the resource. Typically indicates defective programming of the Web server.
408	Request Time-Out	The server took longer than expected to return a page, and timed out. Similar to -5, but generated by the server, rather than Robozilla.
407	Proxy Authentication Required	This code is similar to 401 (Unauthorised), but indicates that the client must first authenticate itself with the proxy. Since Robozilla doesn't use a proxy, this should never occur unless on a faulty server.
406	Not Acceptable	The server cannot generate a response that the requestor is willing to accept.
405	Method Not Allowed	Usually happens when a CGI script doesn't allow GET requests any longer. Backtrack the URL and see if you can find another way to show the data.
404	Not Found	The resource doesn't exist on this server. The page was probably removed.
403	Forbidden	You can't see this resource on the server. The admin may have turned off the pages because of load or for some other reason.
402	Payment Required.	This resource cannot be accessed without payment.
401	Unauthorised	You can't see this resource on the server. Perhaps a password is now required, or the resource you're looking for has moved.
400	Bad Request	Usually occurs due to a space in the URL or other malformed URL syntax. Try converting spaces to %20 and see if that fixes the error.
300: Redirection
303	See Other	The page has a new URL. Update the listing to the new URL.
302	Redirect Temporarily	The page has a new URL temporarily (in theory; in practice, this is often used as a synonym for code 301). Update the listing to the new URL.
301	Redirect Permanently	The page has a new URL. Update the listing to the new URL.
300	Moved	The page has moved to one of several possibilities. Pick the one that's closest to the original page, and update the URL.
0/negative: Connection errors
0	Unknown error	Probably a DNS error.
-1	Unable to Resolve Host	Probably a typo in the host name or they didn't pay their bill for their Domain name.
-4	Can't connect	We can't connect to the HTTP server. The server is there but it didn't want to talk to Robozilla on the specified port.
-5	Timeout	Robozilla connected OK, and sent the request but Robozilla timed out waiting to fetch the page. This happens sometimes on really busy servers.
-6	Bad URL	There was a problem with the format of the URL. Perhaps http:// is missing? Note: when you click on the [edit] link for a URL missing http://, the edit page for the site comes up with http:// helpfully attached by the dmoz software, and the URL link therefore works. You still have to click Update (not "This URL works for me") in order for the update to take effect.
-7	Server Error	The server returned an unknown error code, and is probably misconfigured. The page may still show up okay, but it's a good idea to check it just in case.