Why IPV4 subnets are essential in modern networking

IPv4 subnets stay vital for modern networks as they boost security efficiency and scalability while IPv4 is still widely used.

• IPv4 subnets make networks safer by separating traffic and stopping cyberattacks from spreading.

• They make networks work better by cutting down on broadcast traffic and using limited IPv4 addresses well.

Introduction

Go into any office factory or home and you’ll see devices connected to the internet: laptops printers industrial sensors smart thermostats. Most of these use Internet Protocol version 4 (IPv4) not the newer IPv6. IPv6 was made to fix IPv4’s address shortage but billions of old devices and infrastructure around the world still use IPv4. In this IPv4-heavy world subnets aren’t just something extra they’re necessary.

IPv4 subnets split one big IPv4 network into smaller easier-to-manage parts. Think of a city: if all roads were one huge highway traffic would stop. Cities have streets lanes and roundabouts—smaller “parts” that keep traffic moving. IPv4 subnets do the same for data: they keep information moving well stop cyberthreats from spreading and make big networks easier to handle. To see why they matter you need to first see why IPv4 is still used.

The enduring relevance of ipv4 in modern networking

It’s easy to think IPv6 has taken over from IPv4 but numbers show otherwise. As of 2025 over 75% of internet-connected devices worldwide still use IPv4 addresses according to a report from the Internet Corporation for Assigned Names and Numbers (ICANN) the group that manages global IP address allocation. This isn’t a short-term thing it shows how much old infrastructure there is.

Billions of devices from old routers to industrial control systems don’t support IPv6. Replacing them would cost trillions and most businesses can’t afford that when their current IPv4 networks work. IPv4 will stay in use for at least the next ten years.

It’s not just SMEs. Even big companies and cloud providers use IPv4. Amazon Web Services (AWS) said in 2025 over 60% of its customers’ work still uses IPv4 addresses. IPv4 is deeply part of how businesses build and run their networks and until every device and app supports IPv6—which will take years—IPv4 will be the main part of global networking.

In this situation IPv4 subnets become very important. They help businesses fix IPv4’s biggest problems—too few addresses and hard management—and add security and efficiency that modern networks need.

What is an ipv4 subnet, and how does it work?

Subnetting is about making big networks easy to manage. A 2024 paper on IPv4 network optimisation from IEEE Network says without subnets even a medium-sized network would be messy because you couldn’t track devices control traffic or keep sensitive data safe.

Subnets also fix IPv4’s address shortage. By reusing IP address ranges across different subnets businesses can use their limited IPv4 addresses well. For example a company could use the 192.168.1.0/24 range for its office network and the same range for its warehouse network—since subnets are separate there’s no conflict. This is called “private IP addressing” and it’s a key part of modern IPv4 networking.

Ipv4 subnets enhance network security: the first line of defence

In 2023 a UK retail chain avoided a big data breach after cybercriminals got into its in-store point-of-sale (POS) systems. The attackers used a weakness in the POS software but they couldn’t get to the company’s back-office servers where customer credit card data was stored. The reason is the POS systems were on a separate IPv4 subnet and the servers were on another.

This shows why IPv4 subnets are a must for retail and any industry that handles sensitive data. Subnets create a digital barrier and even if an attacker gets into one part they can’t get to another without getting through extra security tools like firewalls or access lists.

This “network segmentation” is one of the best security steps a business can take. According to a 2024 report from the UK’s National Cyber Security Centre (NCSC) organisations that use IPv4 subnets to split their networks are 70% less likely to have a big data breach. Segmentation limits how far an attack can spread so if one subnet is hacked the damage stays there. Without segmentation an attacker can move freely across the whole network—from a low-importance device like a printer to a high-importance server with customer data.

Subnets also make it easier to set specific security rules. For example a hospital could make an IPv4 subnet for its patient monitoring systems and set rules that only let traffic from that subnet talk to specific servers (like those with patient records) while blocking all other traffic. This works better than trying to secure one big network where one mistake could expose sensitive devices.

IPv4 subnets let you add security where it’s most needed. You wouldn’t leave your front door unlocked just because you locked the back one so you shouldn’t treat all parts of your network the same. Subnets let you lock down important parts while giving less important parts the flexibility they need.

Ipv4 subnets improve network efficiency: reducing congestion and waste

Modern networks handle huge amounts of data from video calls to cloud backups to IoT sensor readings. Without subnets this data would fill the whole network causing jams and slowdowns.

Think of a subnet as a quiet office. If everyone in a building talks at once no one can hear but if you split the building into small offices people can talk without disturbing others. Subnets do the same for data: they keep traffic in the part that needs it so the whole network doesn’t get slow.

The main issue here is “broadcast traffic”—messages sent to all devices on a network. Every time a device connects to the internet (like a laptop looking for a printer) it sends a broadcast message. On a big network with 1,000 devices all 1,000 get every broadcast even if they don’t need to. This wastes bandwidth and slows the network.

Subnets cut down on broadcast traffic by splitting the network into smaller broadcast domains. A 2024 IEEE paper on IPv4 network optimisation found subnetting can cut broadcast traffic by up to 90% in business networks. In a network with 1,000 devices split into four /24 subnets each broadcast only goes to 250 devices instead of 1,000. That’s a big cut in unnecessary data which makes the network faster and reduces delay.

Subnets let businesses use IPv4 even when there are more devices than addresses. Without subnets we would have run out of usable IPv4 addresses years ago because subnets stretch those addresses further so even small businesses can connect all their devices without buying more IPv4 blocks—which are now very expensive.

Ipv4 subnets simplify network management: troubleshooting and scalability

Anyone who’s tried to fix slow internet knows how annoying network troubleshooting is. Imagine a company with 1,000 devices on one network. If the network slows down IT staff have to check every device to find the problem and that could take hours or days.

Subnets make troubleshooting much easier. If a subnet is slow you know the problem is in that part so you don’t have to check 1,000 devices—just 250. That cuts troubleshooting time by 75% or more and for businesses that means less time with no service and happier employees.

Take a university example. A big university might have 10,000 devices: student laptops lecture hall projectors research servers and office computers. If it uses one network a problem with a research server could slow the whole university’s internet. But if it splits the network into subnets—one for research one for lectures one for offices—IT staff can find the problem in the research subnet and fix the server without disrupting classes or office work.

Subnets also make networks easier to grow. As a business grows it adds more devices. Without subnets adding 500 new devices to a 1,000-device network would be messy: more broadcast traffic more security risks and more troubleshooting problems. With subnets the business can just add a new subnet for the 500 devices. The existing network stays fine and the new devices are separate and safe.

Growing easily is key for modern businesses. A startup might have 50 devices now but 500 in a year. IPv4 subnets let them grow without rebuilding their whole network and that’s a big advantage—especially when businesses need to change fast.

Ipv4 subnets support iot and edge computing: the future of networking

The Internet of Things (IoT) is changing industries. From smart thermostats at home to sensors in factories IoT devices are everywhere—and most use IPv4. According to a 2025 report from IDC a market research firm there will be 75 billion IoT devices worldwide by 2025 and 80% of them will use IPv4.

IoT devices bring unique problems to networks. They often have little power limited processing ability and send lots of small data packets. Without subnets these devices would flood the network with traffic causing jams. They also bring security risks: one hacked IoT device could let attackers get into the whole network.

IPv4 subnets fix both problems. IoT devices need their own subnets because you don’t want a smart fridge in a restaurant kitchen on the same subnet as the POS system that handles credit cards. A subnet for IoT devices keeps their traffic separate cuts jams and limits security risks.

Edge computing needs fast local networks. IPv4 subnets let edge devices talk to local servers without sending data across the whole network and that’s important for apps where even a 1-second delay could cause problems—like stopping a factory machine if a sensor finds a fault.

Take a manufacturing plant in Sheffield example. The plant has 1,000 IoT sensors watching temperature pressure and speed on the production line. These sensors are on an IPv4 subnet that only talks to a local edge server. If a sensor finds a problem it sends data to the edge server which shuts down the machine right away—all in less than a second. If the sensors were on one big network the data would have to go to a central cloud server causing a delay that could damage equipment or hurt people.

IPv4 subnets are the main part of edge computing and IoT. Without them these technologies wouldn’t work because they let businesses set up IoT devices and edge servers without disrupting their existing networks—and that’s how we’ll build smart factories smart cities and smart homes in the future.

Ipv4 subnets and ipv6: working together, not competing

Some might ask if IPv6 is the future why use IPv4 subnets? The answer is simple: IPv6 and IPv4 subnets aren’t rivals they work together. For the next ten years (and more) most networks will use both IPv4 and IPv6—a setup called “dual-stack” networking. In this setup IPv4 subnets will keep playing an important role.

IPv6 fixes the address shortage but not network efficiency security or management problems. Even if a business uses IPv6 for some devices it will still have IPv4 devices that need subnets. Subnets make dual-stack networks work by keeping IPv4 traffic separate and efficient.

For example a company might use IPv6 for its cloud apps (which are easy to switch) but keep its old on-site servers on IPv4. Using IPv4 subnets for the servers lets the company keep them secure and managed without disrupting the IPv6 part of the network.

Dual-stack networks are what most businesses use now. IPv4 subnets let them get the best of both: IPv6’s address space and the security efficiency and easy management of subnets for their IPv4 devices.

ICANN agrees. In its 2025 report the group said IPv4 subnets will stay essential as long as dual-stack networks are common. They help businesses switch to IPv6 at their own speed without losing performance or security.

Conclusion

IPv4 subnets aren’t old technology—they’re a key part of modern networking. In a world where IPv4 is still widely used subnets fix the protocol’s biggest problems: they make networks safer by splitting them improve efficiency by cutting broadcast traffic make management easier by simplifying troubleshooting and support new technologies like IoT and edge computing.

They also help with switching to IPv6 letting businesses use dual-stack networks without problems. For SMEs big companies and cloud providers IPv4 subnets are the practical choice—they’re cheap reliable and work with the billions of old devices that power our digital world.

IPv4 subnets will be around for a long time. They’re essential now and will stay essential in the future.

FAGs about ipv4 subnets in modern networking

1. why are ipv4 subnets still needed when ipv6 exists?

IPv6 fixes IPv4’s address shortage but not security efficiency or management problems. Billions of old devices (like old routers IoT sensors) still use IPv4 and don’t support IPv6. IPv4 subnets split these devices cut broadcast traffic and limit attack risks. A 2024 IEEE paper says IPv6 and IPv4 subnets work together not against each other—subnets fix IPv4’s inefficiencies while IPv6 adds more addresses. Gartner also reports 68% of SMEs won’t fully switch to IPv6 in the next five years making subnets essential.

2. how do ipv4 subnets improve network security?

IPv4 subnets create “network segmentation”—splitting traffic into smaller parts. If one subnet is hacked (like a POS system) attackers can’t get to other subnets (like servers with customer data) without getting through extra security tools. The UK’s NCSC found organisations using subnets are 70% less likely to have big breaches. Subnets act as digital barriers limiting how far attacks spread.

3. can ipv4 subnets scale to support large modern networks?

Yes. Subnets let businesses add new parts as they grow without disrupting existing networks. For example a startup with 50 devices can add a new subnet for 500 more devices later. AWS reports over 60% of its customers’ big workloads use IPv4 subnets and a 2024 IEEE paper shows subnets cut broadcast traffic by 90% in business networks—keeping big networks working well.

4. what’s the difference between an ipv4 subnet and a vlan?

A subnet is a logical split of an IP network (based on IP addresses and subnet masks) while a VLAN (Virtual Local Area Network) is a logical split of a switch (based on port numbers or MAC addresses). Subnets control how IP traffic moves while VLANs control traffic on a local switch. They often work together: a VLAN might carry traffic for one subnet making sure both separation and efficient movement. The NCSC recommends using both for maximum security.

5. how do i design an effective ipv4 subnet for my business?

Start by figuring out your needs: number of devices security needs and future growth. Look at resources like Cisco’s IPv4 Subnetting Guide or work with a network architect. Design for growth—leave space for new subnets as your business gets bigger.