The goal of Cisco NAC appliance is to admit to the network only those hosts that are authenticated and have had their security posture examined and approved. The net result of such a thorough examination before allowing connectivity is a tremendous reduction in total cost of ownership (TCO) because only known, secure machines are allowed to connecte. Therefore, laptops that have been on the road for weeks and have possibly been infected or were unable to receive current security updates cannot connect into the network and unleash a Denial of Service (DoS) attack.