CCNA®: Cisco® Certified Network Associate: Fast Pass, Third Edition

6.1. Describe today's increasing network security threats and explain the need to implement a comprehensive security policy to mitigate the threats

You see this a lot—typically, in medium-sized to large enterprise networks, the various strategies for security are based on a some recipe of internal and perimeter routers plus firewall devices. Internal routers provide additional security to the network by screening traffic to various parts of the protected corporate network, and they do this by using access lists. You can see where each of these types of devices is found in Figure 6.1.

I'll use the terms trusted network and untrusted network throughout this chapter, so it's important that you can see where they are found in a typical secured network. ...