Introduction

Any client system (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 (your 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 your 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.

This error 004 occurs in the first step above if our CheckUpDown robot is simply unable to build a valid URL using your site name and the IP port number where your Web server can be found.

Resolving 004 errors

The most obvious reason for an 004 error is that the URL you want us to monitor is fundamentally incorrect. It may have been mistyped or contain an invalid prefix e.g. be 'www.mysipe.com' instead of 'www.mysite.com'. In this case you simply need to correct the URL for your account - start by clicking the 'Manage' button.

If you still see this error for a completely correct URL, it indicates a fundamental problem in our system. Obviously we hope you never see this error for this reason. Typically this involves a one-time fix after which you should never see this error again.