#Cisco subnet mask table how to#

Note: Most people abbreviate the show running-config as show run or even sh run which is also accepted on Cisco devices.įor example, the running configuration on R1 is as shown below: You will want to pay attention to interface configurations, access control lists (if any), NAT configurations if available, and so on. Close without saving meaning that the startup configuration is not altered.īack to our scenario, you can use the show running-config command to quickly get an idea of the configuration on the device.Save the file, meaning that the running configuration overwrites the startup configuration.At this point, the “running configuration” (11 names) is different from the “startup configuration” (10 names). Now, let’s say you open that file and add another name to the list, making it 11 names. Think of this as the “startup configuration”. To understand the difference between the running and startup configuration, imagine a Microsoft Word file that contains a list of ten (10) names. This is as opposed to the “startup configuration” which is the configuration used by the device when it starts/boots up.

This command shows you the entire configuration that is currently running on the Cisco IOS device.

The first command on the list is the show running-config command. Using this scenario, let’s look at five (5) common show commands you are likely to use during your troubleshooting exercise. Since this is a network you are not familiar with, you will need to use some commands to quickly come up to speed on the state of the network, and possibly find and fix the issues discovered. You have been told that the two PCs cannot communicate with each other. The only information you have been given is the IP address table below, which shows how the network should be configured: Device Imagine that you are a freelancer and you have just gotten a project to troubleshoot a network made up of Cisco IOS devices as shown below: To make this article as practical as possible, we will run through a troubleshooting scenario together, using the show commands as we go along, and fixing the issues we find. In this article, we will discuss five (5) common Cisco IOS show commands. Even more important is the skill to know which show command to use to view certain information on the device. However, you will be better off knowing the commands necessary to configure common features such as host names, IP addresses, access control lists, routing protocols, and so on which is where a cisco commands cheat sheet comes in really handy. Of course, I have come to realize that you definitely don’t need to know all the commands available on the Cisco IOS (probably not even realistic that’s what the “?” help is for). A simple 6 step by step guide to subnetting effectively.As a novice in the Cisco networking world, I wondered how I will ever be able to “cram” all the possible Cisco IOS commands.

#Cisco subnet mask table how to#

Step 5: Calculate Valid Hosts | How to calculate number of hosts in the subnet 13/29 located 0 8 16 32 40?ġ3 falls between 8 and 16 and therefore the address is in the valid host range of the subnet 10.20.4.8/29 Where in each increment is the address 10.20.4. Note: 8 is the block size for the subnet so for example, the increments will now be 0 8 16 32 40 and so on! Raise 2 to the power of deduction (8-3 =5 Bits). You might be asking why 8 Bits, 8 Bits are required for each octet. How to Calculate Subnet Mask from IP Address Step by StepĨ Bits – 3 Bits = 5 Bits(Network Bits Turned On) Step by step guide to IP Subnetting Videoīelow is a simple 6 step by step method I use to perform subnetting calculations.ġ: You have been given an IP Address 10.20.4.13/29 and been asked to find out the following pieces You can read more on the subject broadly from Cisco’s website here. Have you been faced with a task laced with many prefixes you find intimidating? Well, you are in the right place at the right time to improve your understanding of subnetting once and for all.

In as much as there are a great number of articles on the subject of subnetting, I have also taken a bold step in creating a step by step guide “How to Calculate Subnet Mask from IP Address Step by Step” to bring you the understanding I have gained in the real world where subnetting is concerned.