David Davis

If you are used to working with home networking gear you are used to an integrated device that “does it all”. On a home network, you may have one box that is a cable/DSL modem, router, firewall, switch, and wireless access point all in one. It is amazing all the functions they can fit into…

Recently, a fellow Cisco administrator told me about a tool he had used to reset a password on a router. He had forgotten the line vty password and the enable password. He could not log in to the router. He did, however, know the SNMP Read/Write password. Using a freeware tool dubbed “Cisco SNMP Tool”…

Preventing network loops with Spanning-Tree Protocol (STP) 802.1d Have you ever had a loop in your LAN?  You don’t want one and neither do your users.  A loop in your LAN can bring down the whole network.  You can avoid a loop by using Spanning Tree protocol (STP).  Let’s find out what Spanning Tree is,…

The ping command is irreplaceable when it comes to troubleshooting. At some point, you will undoubtedly use this command to solve a networking problem. But how do you properly use this command in the Cisco IOS? There is more to it than you might think. What Are The Basics of Ping? The ping command works…

In a previous article, we explained the OSI model and how it works. In that article, we went over how the OSI model is a standard theoretical model for how networking hardware, software, protocols work together. What we didn’t discuss in that article is how the OSI model can help you in your day to…

Most Cisco devices do not have a graphical Web-based interface by default.  You must configure them from the command line using the serial-based console port on the switch or router.  While there are a variety of serial terminal emulation programs available, most people use HyperTerminal to do this because it is included free with Windows. …

Many of us use switches every day but never really think about how they work. Whether you are studying to become a CCNA or just want to learn more about how a switch really functions, this article is for you. Hubs vs. Switches Prior to switches, Hubs were the standard for connecting devices on a…

In Part 1 of this article, we explained how access-lists work. In this article, we’ll take a sample network and explain how to create and apply an access-list. Remember that an Access-List (ACL) is used to specify network traffic. Once you specify traffic with an ACL, you can then do a variety of things with…

A Cisco IOS Access-List (ACL) is used to specify network traffic. Once you specify traffic with an ACL, you can then do a variety of things with it. For example, you could allow it, deny it, limit it, or use it to restrict routing updates. In this article, we will learn the basics of Cisco…

As a network administrator, you must be able to configure your routers to route traffic across the network. Static routes are commonly used on routers to accomplish this. For a network admin, knowing how to use a static route is a requirement. Let’s learn about static routes, and how to properly use them. Static vs….