Doug Vitale Tech Blog

Posts Tagged ‘subnetting

Understanding and performing IPv4 subnetting

Subnetting – it’s the subject that IT professionals love to hate. Believe it or not, the frustration that it caused me as a student years ago made me question whether I wanted to go into the information technology (IT) field. Furthermore, with the availability of many subnet calculator programs and subnetting websites, the ability to manually perform subnet calculations may seem superfluous at first. However, a solid understanding of IP subnetting will not only allow IT pros to create appropriately-sized networks in the absence of specialized software and web applications (on paper, for example), but given IP’s foundational role in modern computer networks and the global Internet, it behooves us to keep our comprehension of this protocol sharp. Lastly, if you plan on obtaining a networking certification like the Cisco CCNA, you are just going to have to master the material below.

The purpose of this article will be to thoroughly explain how IP subnetting works and to provide some relevant examples. Therefore a detailed analysis of all the workings of IP, such as packet structures, packet switching, and routing will not be provided. However, we will review what the Internet Protocol (IP) is, how it works, and what purpose it serves on networks. We will focus solely on Internet Protocol version 4 (IPv4) which is the version of IP that has powered the Internet revolution and remains the most widely utilized networking protocol today.

A subnetted network

A subnetted network using variously sized subnet masks

Computers must share a common protocol to communicate, and nowadays IP has become ubiquitous on nearly all operating systems. So what does IP do? Simply put, IP allows computers to locate and facilitate communications with other hosts that are either on the same logical network or on separate, distinct networks (for instance, networks such as those owned by different organizations – businesses, universities, Internet service providers, etc.). IP provides for this communication by enabling the routing of data packets between sources and destinations, often through multiple intermediary hosts.

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Written by Doug Vitale

March 5, 2013 at 3:50 PM

LanTricks LanCalculator

LanCalculator from LanTricks is the program that everyone wishes he had during the CCNA exam. From a given IP address and subnet mask, LanCalculator will tell you the network IP address, the range of host IP addresses, the subnet broadcast address, and the amount of hosts allowed on the subnet. It will also convert addresses to binary.


The LanCalculator v1.0.2.29 user interface

The latest version of LanCalculator is and does not appear to have been updated since June 2006.

Although the download page claims that LanCalculator works only with Windows 2000/XP/2003, it works fine on my Windows 7. However, LanCalculator does not support IPv6.

Written by Doug Vitale

November 14, 2011 at 1:47 PM

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