Troubleshooting a serial interface

The show interface serial command returns one of five possible states. You can identify any of the following five possible problem states in the interface status line:

Ex4 Chapter 5 - ACLs

Ex4 Chapter 3 - Frame Relay

Ex4 Chapter 4 - Network Security

When discussing network security, three common factors are vulnerability, threat, and attack.
Vulnerability is the degree of weakness which is inherent in every network and device. This includes routers, switches, desktops, servers, and even security devices.
Threats are the people interested and qualified in taking advantage of each security weakness. Such individuals can be expected to continually search for new exploits and weaknesses.

Ex4 Chapter 2 - PPP

Ex4 Chapter 1 - Introduction to WANs

A WAN is a data communications network that operates beyond the geographic scope of a LAN.

Here are the three major characteristics of WANs:
 - WANs generally connect devices that are separated by a broader geographical area than can be served by a LAN.
 - WANs use the services of carriers, such as telephone companies, cable companies, satellite systems, and network providers.
 - WANs use serial connections of various types to provide access to bandwidth over large geographic areas.

Using Traceroute

Traceroute is the program that shows you the route over the network between two systems, listing all the intermediate routers a connection must pass through to get to its destination. It can help you determine why your connections to a given server might be poor, and can often help you figure out where exactly the problem is. It also shows you how systems are connected to each other, letting you see how your ISP connects to the Internet as well as how the target system is connected.
This tutorial was written for users of premium Usenet services, but can be useful for anyone wanting to learn to use traceroute.