We use Netflow to control traffic, when i want to resolve the IP addresses from netflow's outside destinations list, i get local google cache server's IP address, never the web sites that users has visited, how do i find out the actual web site that user has visited?
The web site URL is not a network or transport-layer entity. It is visible only at the application layer and may be encrypted anyway. Don't forget that a URL can resolve to many IP addresses, and a single IP address may be used for multiple web servers.
The most reliable way to understand what sites are visited is to use a web proxy.