1. What is the typical relationship among the un-trusted network, the firewall, and the trusted network? 2. What is a circuit gateway, and how does it differ from the other forms of firewalls? 3. What is a hybrid firewall? 4. List the five generations of firewall technology. Which generations are still in common use? 5. What is a VPN? Why is it becoming more widely used? 6. What is RADIUS? What advantage does it have over TACACS? 7. Describe how the various types of firewalls interact with the network traffic at various levels of the OSI model.