While NAC won't stop a determined user bent on introducing viruses and worms into your network, looking back at my father's advice from the beginning of this article: NAC doesn't need to. If NAC is only successful in preventing the systems that arent trying to be active conduits of malicious traffic from attacking the network and keeping unauthorized systems off the network, it will have already performed a valuable service for an organization's IT infrastructure. NAC surpasses most other recent security innovations in importance and utility. Organizations hoping to enforce endpoint admission and compliance policies should give NAC careful attention and begin considering how such a technology would work in their environment.