One of the first steps in troubleshooting a network, is to identify if the lines (links) are operational. On a Cisco router, the quickest way to see all lines as well as their status is by using the “show ip interface brief” command. In the live demo below, you will see that I have […]
I have recently been asked quite a few times, “How do you start your own website?” The first and most important, is to find a domain name that you want, and is still available. This can be done in quite a few places but before you even begin looking you need to decide what extension […]
In order to set up an IP address on an interface, we need to be in the interface level of the command line. This is a level within the global configuration level. From global configuration mode, we can enter the ‘interface serial 1/0’ command. If you are unsure of what interfaces are on the router, […]
Every Cisco device has 2 sets of configurations. On routers and switches these configurations are called ‘running-config’ and ‘startup-config’ When you make any changed on a router or switch, the change applies to the running-configuration and will affect the router or switch with immediate effect. However, if the device is reloaded for whatever reason, all […]
It is advisable that on all your devices in your network, you have a disclaimer or message that appears when someone connects to your device. There have been many cases over the years where a hacker has gained access, been caught, and got away with it since there was nothing in place informing that they […]
Using the Pipe ‘|’ is by far one of the most important things you can learn on a Cisco device. I never really appreciated this command when I started out in Cisco, as it seemed to take me longer to use it, and I didn’t get to see what I was looking for. In hind […]
One of the most annoying things I kept doing when I started out in Cisco, was constantly typing ‘show’ commands when in the wrong level of the configuration. By default, Cisco only allows you to do a ‘show’ command when you are in privileged mode (AOIP.ORG#). This can be frustrating when you are multiple levels […]
By default a Cisco device does not have any passwords on it, so access to the console is open by default, and anyone connecting to the device is able to access privileged mode (enable mode). This of course is a security risk and one of the first things that should be done with a new […]
The console is a physical port on a Cisco device that allows us to connect to the device using a directly connected cable from your PC. It is the easiest and most reliable method of connecting to a Cisco device as it does not require configuration on the device and is enabled by default. It […]
VTY (Virtual Terminal Lines) are used when you wish to telnet into a router remotely. In order for the router to allow telnet connections, the VTY lines need to be configured with a password, which is not a default setting. If you were to try connect to a router with telnet and the VTY password […]
So as we have seen in the post Class-full IP addresses, IP addresses are usually put into Class A,B or C. We have also seen that in 1990 CIDR was invented which allowed us to use Classless addresses for routing, and also saving of address spaces. So what is class-less then? If we have […]
CIDR was invented in 1990, and was the change that allowed routers to use classless addresses to route traffic instead of class-full addresses. This helped a huge amount as before its invention, routers could only route traffic based on full classes. If we look at Class A address for example, there are only 126 of […]