This Simple guide to Network Segmentation.
And when you are learning about networking, or about some networking certification (like the CompTIA Network+ or the Cisco CNA) or just basic understanding of how computers can talk to each other on the internet you will one day come across a confusing subject:
Subnetting.
This is threatening in itself as a title. Subnetting is however, just a logical process of organizing the network in a system that supports the efficient communications that are safe and extendable too. Subnetting is not a formulae as so much as it has some basic rules that you can be able to discover patterns of.
We shall begin by a simple tutorial in which we shall step by step subnetting and we shall require no experience in mathematics and in which we shall not use any difficult language.
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What Is Subnetting?
Subnetting can be described as process of breaking down a large network into smaller networks that can easily be managed and they are known as subnets.
Suppose the subnet will be of the part of a large office building which consists of separate divisions:
• One floor for HR
• One floor for Finance
• One floor for IT
The company has internal communication, which exists in individual departments and at the same time it has the departments under it. The subnetting is not that much different either except that it applies the arrangement of the devices to a bigger network into logical grouping.
This improves:
• Network performance
• Security
• Traffic management
• IP address efficiency
Without subnetting, huge networks would be anarchy and snarl-up.
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Why Subnetting Is Important
The main reasons of subnetting are as follows:
1. Reduces Network Traffic
This will be congested in a big network whereby all the devices in the network will be sending messages to other devices. Subnetting will ensure that the unnecessary traffic is limited to smaller units.
2. Improves Security
Subnets act like barriers. The sensitive departments (like finance servers) may be separated with the help of general user devices.
3. Makes Trouble shooting easy.
Network admins do not require waiting until they can be conscious of when the issues have been encountered.
4. Proper usage of IP Addresses.
Subnetting will as well eliminate the unnecessary use of IP address by simply providing the necessary use.
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IP Addresses In a Nutshell.
In the absence of knowledge of IP address, subnetting cannot be subnetted.
The appearance of an IPv4 address is similar to the one presented below:
192.168.1.10
It contains 4 numbers towards 0 -255. Such numbers are called octets.
Any IP address is divided into two:
– Network portion- network definition.
• Host portion – determines a device in that network.
The subnetting is the alteration of percentages of addresses within the network and number of hosts within the network.
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What Is a Subnet Mask?
A subnet mask tells devices:
Host and IP address network What is the network?
Example subnet mask:
255.255.255.0
This is also displayed on the CIDR notation as:
/24
Classless Inter-Domain Routing (CIDR) is just another shorter name that is used instead of subnet masks.
Common Subnet Masks
CIDR Subnet Mask Network Hosts.
/24 255.255.255.0 254
/25 255.255.255.128 126
/26 255.255.255.192 62
/27 255.255.255.224 30
/28 255.255.255.240 14
Notice a pattern?
The smaller the subnet, the smaller the host addresses.
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Subnetting principle (Easy Explanation).
Subnetting process involves the use of bits of sender component of an IP address to create other networks.
And wosupposethe had ye loaned out a bit more land than thou can fatten:
• Originally: 1 large farm
• Division: 4 smaller farms.
You have had a reorganization, you have not plowed more ground.
Such is also applied to the IP space, in subnetting.
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Status: an A/24 Network subnetting.
Suppose we shall be provided the network in the following:
192.168.1.0/24
This means:
• Total addresses: 256
• Usable hosts: 254
And suppose you desired having 4 smaller networks.
To accomplish this, you take 2 bits of host position on loan.
New subnet:
/26
Each /26 network has:
• 64 addresses total
• 62 usable hosts
Your new subnets become:
192.168.1.0/26
192.168.1.64/26
192.168.1.128/26
192.168.1.192/26
All of them are autonomous networks.
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Broadcast Address and Network address.
The subnet consists of two special addresses:
1. Network Address
This adds to its exceptionality of the subnet.
It can not be ascribed to equipment.
Example:
192.168.1.0
2. Broadcast Address
This is broadcasted in the subnet.
Neither can citizens be placed in a machine.
Example:
192.168.1.63
So usable hosts fall between:
192.168.1.1 → 192.168.1.62
Such is what makes usable hosts always:
Total addresses – 2
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Shortcut Rule of Subnetting.
You need not know all by heart.
And here is a little thing that gamblers will take:
Magic Number Method
The subnet mask less 256 = -.
Example:
/26 = 255.255.255.192
256 – 192 = 64
This number (64) tells you:
By 64 steps all the subnets are added.
So the networks go:
0
64
128
192
That’s it. No complex math required.
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Real-World Example
The company has the following 3 departments:
• Sales → 50 employees
• IT → 40 employees
• HR → 10 employees
The company does not use extensive network and locates all the devices in a subnets:
• Sales subnet: /26 (62 hosts)
• IT subnet: /26 (62 hosts)
• HR subnet: /28 (14 hosts)
It will prevent unnecessary overloading of traffic and will also improve performance.
Subnetting also has the capability of creating networks as per the real needs.
The merits of studying Subnetting.
Subnetting: The idea that you can subnet: is not that hard, even to the beginner.
Career Advantage
Subnetting This is a very necessary networking requirement and is needed in:
• Network engineering
• Cybersecurity
• System administration
• Cloud infrastructure
Certification Preparation
The subnetting testing is performed in some detail in:
• CCNA
• Network+
• AWS networking
• Azure networking
Better Network Planning
Subnetting will be the knowledge that will make you develop scaling and secure systems.
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Common Beginner Mistakes
No one is a good subneter to begin with. That’s normal.
The pitfalls to be avoided include the following:
1. Forgetting to Subtract 2
Always remember:
Available addresses = total address -2.
(Network + broadcast)
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2. Mixing CIDR and Subnet Mask
Know that they are one thing:
/24 = 255.255.255.0
Just different formats.
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3. Overcomplicating It
Subnetting is not a high level math it is pattern recognition.
Focus on learning organization.
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Practice Tip for Beginners
The easiest way of learning to subnet:
👉 Repetition
Start with one network:
192.168.1.0/24
Practice breaking it into:
• /25
• /26
• /27
• /28
Write out:
• Network address
• First host
• Last host
• Broadcast address
Do this daily for 10 minutes.
It will only take a little less than 7 days before it becomes instinctive with subnetting.
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Final Thoughts
Subnetting is something that is hard to grasp until the time when it comes to your mind and once it comes to mind that it is one of the most rewarding networking skills.
Essentially subnetting involves:
Organize network to make the communication smart.
It improves performance, security besides enabling the networks to scale successfully. Any of the modern networks, the routers within the home and out the other side of the globe clouds all the way through, subnet.
The key is to take it slowly:
• Understand IP structure
• Learn subnet masks
• Dividing networks into bits.
There is no need to be acquainted with it in a day. Demolition is not like half a practice.
And remember:
Subnetting too was the curse of all professional network engineers.
you are everywhere which you should be.
