Step-1. Created a visual force page as HTML5 by introducing the ‘doctype’ parameter.
Step-2. Created a site for the visual force page to access from external environment.
Step-3. Created a manifest file to cache the created visual force page and saved it as ‘test.appcache’
Step-4. Go to IIS and create a new MIME type ‘text/cache-manifest’.
Step-5. Add the manifest file to the root.
Location – C drive ->inetpub->wwwroot.
Step-6. Now hit the site URL in the browser. The visual force page should open in browser
Step-7. Close the browser and disconnect the internet connection. Try accessing the same in a new browser. Page opens from cache.