You need to commit to memory the respective values of each of the bits in an octet, as shown here:Īs you can see, a bit’s position in an octet determines its value. To clearly comprehend IP subnetting, though, you need to be able to “see” dotted decimal addresses in binary format. We use this notation because it is visually easier for our brains to process.
When represented numerically, IP addresses are said to be in dotted decimal notation, for example 192.168.10.25. The four fields in an IP address are actually called octets, from the Latin word for eight, octo. This is not a good idea!Įach of the four fields in IP address contains eight characters (called bits), meaning that IPv4 is based on 32-bit addresses (8 bits x 4 fields = 32 bits…and remember, eight bits makes a byte). When I mentioned earlier the discouragement I felt at not being able to subnet, it was because I had a poor understanding of binary and I was trying to subnet anyway. It is crucial to understand this if you want to make sense of subnetting. In other words, despite its standard numeric appearance, IP addressing is actually done at the binary level. So if you look at an IP address such as 192.168.10.25, how would you know if it is a host or network address? The answer is to first realize the binary nature of IP addressing. If your phone number were (908) 469-6151, 908 would be like the network address while 469-6151 would represent your host device (your telephone). Put another way, network addresses can be seen as analogous to telephone area codes.
POWER OF 2 TABLE SUBNETTING CHART ZIP
Your zip code, however, would be your “network address” because it refers to your municipality, a grouping of buildings just as networks are groupings of hosts. Your street number + street name would be your “host address” because it refers specifically to your residence, a single building or unit. Think of your residential address, for example. A network IP address, in contrast, does not refer to a single host but to a collection of hosts. A host IP address specifies a single host or device on a network, such as the network interface card ( NIC) on a server or your laptop (yes, it is possible for hosts to have more than one NIC and hence, multiple IP addresses). The first prerequisite to understanding IP subnetting is to grasp the difference between host addresses and network addresses. To accomplish the goals of host identification and packet routing, IP relies on an addressing scheme in which individual hosts as well as collections of hosts (networks) are assigned unique IP addresses. IP provides for this communication by enabling the routing of data packets between sources and destinations, often through multiple intermediary hosts. 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.).
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.Ī subnetted network using variously sized subnet masksĬomputers must share a common protocol to communicate, and nowadays IP has become ubiquitous on nearly all operating systems. However, we will review what the Internet Protocol (IP) is, how it works, and what purpose it serves on networks. Therefore a detailed analysis of all the workings of IP, such as packet structures, packet switching, and routing will not be provided. The purpose of this article will be to thoroughly explain how IP subnetting works and to provide some relevant examples. Lastly, if you plan on obtaining a networking certification like the Cisco CCNA, you are just going to have to master the material below.
POWER OF 2 TABLE SUBNETTING CHART SOFTWARE
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. Furthermore, with the availability of many subnet calculator programs and subnetting websites, the ability to manually perform subnet calculations may seem superfluous at first. 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.
Subnetting – it’s the subject that IT professionals love to hate.
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