The Web server (running the Web site) thinks that there has been too long an interval of time between 1) the establishment of an IP connection (socket) between the client (e.g. your Web browser or our CheckUpDown robot) and the server and 2) the receipt of any data on that socket, so the server has dropped the connection. The socket connection has actually been lost - the Web server has 'timed out' on that particular socket connection. The request from the client must be repeated - in a timely manner.
408 errors are often difficult to resolve. They typically involve one-off variations in system workload or operations.
If you see persistent 408 errors, the first thing to consider is the workload on the Web server - particularly around the time the 408 errors were generated. If this is light, then you also need to consider workload on the client system. If the computer systems on both ends of the socket connection seem to be running normally, then temporary Internet surges may be to blame.
Our service monitors your site for HTTP errors like 408. This error is highly unlikely to occur on your CheckUpDown account, because there is usually only a tiny interval of time (milliseconds) between our 1) opening of the socket and 2) writing the HTTP data stream through that socket. In exceptional circumstances, this interval may increase because of some operations on our computer systems e.g. we temporarily suspend an executing process and this happens immediately after the socket was created. Or the two steps may follow quickly on our systems, but the second step encounters an unreasonable delay on the Internet. The acceptable interval between the two steps could also be set very low on the Web server e.g. the Web server is very busy, and has become a bit 'impatient' with attempted connections it views as a bit slow.
Any of these conditions may generate an 408 error. But they are all fairly unlikely to occur. In normal IP communications, the time interval between the two steps should be much less than 10 seconds, which should be completely acceptable to the Web server. Please contact us (email preferred) if you see persistent 408 errors, so that we can agree the best way to resolve them.
Any client (e.g. your Web browser or our CheckUpDown robot) goes through the following cycle when it communicates with the Web server:
This error occurs in the final step above when the client receives an HTTP status code that it recognises as '408'.