Error 400 - Bad request.
Error 401 - unauthorized request.
Error 403 - forbidden.
Error 404 - Not found.
Error 500 -Internal error.
Error 501 - Not Implemented
Error 502 - Bad Gateway
Error 503 -Service unavailable.
Error 504 - Gateway Time-Out
Error 505 - HTTP Version not
supported/DNS Lookup Fail/
unknw host
Error 500-599 - Server Errors.