Errors reported by CheckUpDown
Introduction to errors
Any client (e.g. your Web browser or our CheckUpDown robot) goes through the following cycle when it communicates with your Web server:
Obtain an IP address from the IP name of your site (the site URL without the leading 'http://'). This lookup (conversion of IP name to IP address) is provided by domain name servers (DNSs).Open an IP socket connection to that IP address.Write an HTTP data stream through that socket.Receive an HTTP data stream back from the Web server in response. This data stream contains status codes whose values are determined by the HTTP protocol. Parse this data stream for status codes and other useful information.An error may occur in any of the above steps. Our CheckUpdown robot isolates any error and reports it as an error code for your account (as a clickable link) along with details of when the error was detected.
The error codes the client may receive are given below - follow the URL for each to see further discussion of the error and what further action we recommend.
0?? errors
Errors with a code in the range 001-099 indicate a fundamental failure to communicate, typically in the early steps above. Note these errors are not defined in the HTTP protocol - they are specific to our CheckUpDown service.
001 - Unknown Host002 - I/O Exception003 - Undefined HTTP Status Code004 - Bad URL005 - Host not reachable006 - No connection007 - I/O Interrupt008 - Socket failure009 - SSL secure socket failure010 - Check word not found011 - Socket Timeout
3?? errors
Errors with a code in the range 300-399 indicate a redirection of the Web site URL. As of September 2000, CheckUpDown follows some URL redirections (301, 302, 303, 307) automatically, so these should no longer be reported as an error.
300 - Multiple Choices301 - Moved permanently302 - Moved temporarily303 - See other304 - Not modified305 - Use proxy307 - Temporary Redirect
4?? errors
Errors with a code in the range 400-499 occur where the Web server - incorrectly or not - dislikes the HTTP data streams that the client sends to it. Quite rare.
400 - Bad request401 - Unauthorized403 - Forbidden404 - Not found405 - Method not allowed406 - Not acceptable407 - Proxy authentication required408 - Request timeout409 - Conflict410 - Gone411 - Length required412 - Precondition failed413 - Request entity too large414 - Request URI too long415 - Unsupported media type416 - Requested Range not satisfiable417 - Expectation failed
5?? errors
Errors with a code in the range 500-599 occur where the Web server reports an internal error in its operations.
500 - Internal server error501 - Not implemented502 - Bad gateway503 - Service unavailable504 - Gateway timeout505 - HTTP version not supported
