Lancaster University

Cache Configuration for WWW Browsers

What is Web Caching?

The concept of web caching is simple: when a Web page is requested, it is saved to a local disk. If the page is required again, the disk copy is used rather than waiting for a copy to be pulled across the network. This technique is used in all modern browsers such as Netscape Navigator and Internet Explorer.

With a web cache, users request pages from a local cache server instead of direct from the internet source. The local cache server gets the page from the internet on behalf of the user, saves it on disk and forwards a copy to the user. Subsequent requests from other users of the cache get the saved copy, rather than having to wait for a copy to be pulled across the internet. This means that regularly used pages appear much faster and the requests do not consume Internet bandwidth.

There are several other terms in use that you may see referred to: 'proxy server', 'proxy cache', 'www proxy' and other variations all mean the same thing.

Why you must use it

UKERNA, the national academic network administrator, charges for the amount of traffic coming INTO the university on the transatlantic link in an effort to reduce demand and offset the costs of increasing capacity. World Wide Web traffic constitutes about 80% of this traffic: by using a campus-based web cache we can reduce the amount of transatlantic WWW and therefore signicantly reduce our bill.

In order to reduce web traffic all requests to external web pages MUST go through the web cache.

If you want to access offsite pages then you MUST reconfigure your browser.

Configuring your browser

To Configure your browser to use the web cache, you need to follow the step by step instructions below. This will enable you to automatically configure your browser to use the Lancaster web cache for all appropriate web pages.

By using this method any future changes to the way the web cache works will be directly reflected in your browser set-up without you having to make any changes.

Step-By-Step Instructions

Click on one of the links below to get specific instructions on how to set up caching for your web browser.

If you are not sure exactly which browser you are using you can usually find this out by selecting 'Help' (normally the rightmost item in the menu bar at the top of the window) then 'About...' This should then give you the browser type and version.

Alternatively, the 'autodetect' option should work for most people and automatically take them into the instructions for the browser they are using.

• Attempt to autodetect your browser

• Windows (95/98/NT4/2000/XP)
  • Microsoft Internet Explorer 2 (does not support autoconfig)
  • Microsoft Internet Explorer 3 (does not support autoconfig)
  • Microsoft Internet Explorer 4
  • Microsoft Internet Explorer 5
  • Microsoft Internet Explorer 6
  • Microsoft Internet Explorer 7
  • Netscape 1
  • Netscape 2
  • Netscape 3
  • Netscape 4
  • Firefox 1
  • Opera 5.x (does not support autoconfig)
  • Opera 6.x
  • Opera 7.x
• Macintosh
  • Microsoft Internet Explorer 3 (does not support autoconfig)
  • Microsoft Internet Explorer 4 (does not support autoconfig)
  • Netscape 4
  • Mac OS X (browser-independent configuration)

Troubleshooting

If you are unable to connect to any web sites off campus, then you need to check that you have configured your browser correctly.

If you can connect to some web sites off campus, but have problems with others, it may be because some WWW Servers perform an authorisation check based on the client's IP address. Accessing such servers via a cache confuses them and they may deny access. If you encounter problems with such a server, please contact the ISS Help Desk for a recommended course of action.

General instructions

If your browser is not one of the ones covered by the previous section the following may be of help.

• If your browser supports it, use the proxy auto configuration URL (sometimes referred to as a 'PAC script'):
  http://wwwcache.lancs.ac.uk/
  This will use the web cache in the most effective way.
• Alternatively, if your browser does not support autoconfig, use the following cache settings:

  Hostname:	wwwcache.lancs.ac.uk
  Port:	8080
  No Proxy For:	*.lancs.ac.uk

  Some browsers use different names for the different settings. Also, some browsers do not support 'no proxy for' or require a different format to that given here. You should check the documentation for your browser if you are unsure.

Frequently Asked Questions

What happens about pages that are updated regularly. Surely the cache will serve stale information?

No it won't. Quite a lot of effort has been put into web caches to ensure that this will not happen for most pages, even where the content is dynamic or updated regularly. If you suspect that there may be a more recent version of a page it is worth using the 'reload' button on your browser - this will cause the page to be unconditionally reloaded from the original server.

What happens if I access an Internet page which is password protected: will my data also be stored on the web cache?

No it won't. Only pages that have unrestricted access will be cached. Password protected pages will be served by the cache but will not be stored.

Student Network Instructions

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