• Novell BorderManager Proxy Server is unable to access an Internet page. When it attempts to do so, one or more of the following messages display:
  
  Page cannot be displayed.
  
  502 bad gateway error.
  
  504 gateway error.
  
• Your Internet browser is returning an invalid response from an upstream server while it is trying to fill a request. A separate browser page may open with the "502 bad gateway" error message.
  
• Your proxy server has encountered an invalid response while trying to contact upstream Internet traffic. The DNS server may be unreachable.
  
• You are having problems connecting to the DNS server. The message "DNS name server unreachable" indicates that the proxy has lost communication with the DNS server or can't connect to the DNS server.
  
• The BorderManager Proxy Server is opening an error page that is behind the top web page or minimized on the task bar. BorderManager error pages have a large red header on them.
  
• Your workstations may be out of memory resources, or may be causing the Internet browser to not respond to a request for some reason.

• By default, Internet access through the Novell BorderManager Proxy Server uses a port 8080, which allows HTTP Internet traffic. The Internet browser needs to be set up to use a Proxy Server with port 8080.
  
• The syntax in BorderManager's SYS:ETC\RESOLV.CFG file may be incorrect.
  
• Some error web pages do not make it through BorderManager; instead, they appear as "502 bad gateway" messages.
  
• DNS resolution may have failed for the URL going through hierarchy.

• Try refreshing or reloading the web page: Click the "refresh" button on your browser's toolbar. Sometimes refreshing or reloading the request resolves the problem.
  
• Configure proxy services for Internet access: Make sure your proxy services have been configured for Internet access. For persistent errors, verify that your access is not blocked by a firewall or packet filtering at the proxy server.
  
• Check your BorderManager configuration: Check for communication problems and timeouts in the BorderManager setup. Check the syntax of the SYS:ETC\RESOLV.CFG file to make sure that it is correct. If the DNS cannot resolve the hostname specified in the request, or the DNS host name resolution failed, the syntax may be incorrect. (For example, there may be an extra period in the domain name, or the hostname entered in the request may be incorrect.)
  
• Close BorderManager error web pages: Close any BorderManager Proxy Server error web pages to free up memory resources. Check the task bar for open proxy server error pages and close them if found.
  
• Set up your IE browsers to run through the Novell BorderManager Proxy Server:
  
  1. Open Internet Explorer.
  
  2. Click Tools > Internet Options > Connections > LAN Settings > Use a Proxy Server.
  
  3. Enter the port number (8080 by default), hostname, and IP address of the Novell BorderManager 3.7 Proxy Server in the proxy field.
  
  4. Click Apply.
  
• Install support packs for BorderManager:
  Novell Inc. periodically releases new support packs for BorderManager. Check their web site periodically for patches. Install the latest support packs and keep them up to date. Go to the Novell Product Downloads page.

• HTTP Error Status: 502 Bad Gateway. Host name resolution failed local host.
  
• Information Alert. Status: 502 Bad Gateway. Description: DNS Name Server is unreachable... URL: http:/localhost: 1028/...
  
• The requested URL could not be returned while trying to retrieve the URL: http://localhost1034. The following error was encountered: .connection failed.
  
• The requested URL could not be retrieved while trying to retrieve the URL: http://localhost.../ The following error was encountered: Unable to determine IP address from host name for localhost...
  
• Error URL filter configuration Http//localhost: 1046
  
• Action canceled. Internet Explorer was unable to link to the Web page you requested. The page might be temporarily unavailable. Please try the following...
  
• IE could not open HTTP:\\LocalHost:xxxx\. Connection with Server could not be established.

• Make sure Internet Explorer 6.0 with Service Pack 1 or Internet Explorer 7.0 is installed on the workstation.
  
• Make sure the TCP/IP protocol is installed on the workstation.
  
• If you have a proxy server or use web filtering or security software, configure Internet Explorer to bypass the proxy server. Follow the steps below.

• While answering questions, the browser gets an error message that a script on the page is running slowly. There will usually be two buttons that give you the option stopping the script or letting it run. Different browsers word the message differently. Electing to stop the script will usually result in not being able to continue to the next question. Electing to let it run will give you the same error.
  
• Another possible error dialog talks about re-posting the form data with a Retry and Cancel button and again neither option is effective.
  
• A third symptom of this problem is that the browser will become very slow to respond to user events.

• The page that displays questions for the students is very complicated, with many Frames and Scripts. The scripts do some very intensive work. Sometimes a browser will decide the script is taking to long and display the error message.
  
  
• Other causes can be related to Extensions that are installed on the browser or options the are turned on (such as the phishing filter in Internet Explorer 7) that slow the browser down.
  
• There is a known problem in IE 7's phishing filter and will manifest as various error dialogs while a student is doing an assignment. You can read about the IE problem
  here: http://support.microsoft.com/kb/928089

If using Internet Explorer 7, turn off the phishing filter.

• Click the Tools drop down list and select Phishing filter -> Phishing filter settings. This will open the Internet Options dialog.
  
• Scroll down to the Security section (close to the bottom of the list)
  
• You will find some radio buttons under a heading Phishing Filter, select the top Radio button (Disable Phishing Filter)
  
• Click Apply, then OK.
  
• Restart your computer.

It may be necessary to re-create the assignment and handout again as the original error may have corrupted the assignment.

Upgrade your Internet Explorer:

To update IE 7, use this link : http://support.microsoft.com/kb/928089

After a successful update, the version number should be at least 7.0.5730.11

For FireFox Browsers:

To see if an extension is the problem, try removing all of your extensions. To remove an extension from Firefox, select Tools > Extensions to open the Extension Manager.

In the Extension Manager, select each extension and click the Uninstall button. You may need to close and then reopen Firefox or even restart your computer for all changes to take effect.

If the removal of the extensions resolves the problem, then you can add back in each extension one at a time and test until the problem reappears. The last extension you added back in will be the cause of the problem and you will need to Uninstall it again. NOTE that more than 1 extension could be problematic, so you should continue adding each extension 1 at a time and testing.