WAN documents are stored locally in cache with a document expiration date. Ideally, content is unchanged prior to the expiration date and has changed after the expiration date. When requesting to view a WAN document while on-line, the document first is displayed from cache for display and verify mode. The web browser then sends a request to the web server to verify whether the document has been modified. If still valid, then the document is already displayed and time has been saved. If invalid, then the document is downloaded from the web server, stored in cache, and optionally or automatically displayed in place of the invalid document. A signal is communicated to the user, for example, to give the option to reload the document. Because document expiration times may be absent or unreliable, a soft and a hard expiration time are derived and adjusted dynamically based upon their reliability.