What Is Subnetting? What Are Subnet Masks? All Your Questions Answered

When you’ve got many computers and other devices on a single network, things can get complicated. Excess traffic takes a toll on processing power and causes networks to run slowly. If you’re operating a network and having high performance is important to you, slow speeds just won’t do. 

This is where subnet masks come in. What’s a subnet mask? Stick around, we’ll answer key questions about subnetting and subnet masks — let’s get technical!

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What Is Subnetting?

Subnetting involves dividing large networks into smaller subnetworks or “subnets.” Large networks with many computers are more difficult to maintain. They often get congested with traffic leading to less efficient communication. 

Subnetting achieves better network efficiency by breaking a large network down into manageable smaller networks. When you create subnets, you can optimize available IP addresses and improve network performance.

Subnetting has many benefits but it requires some extra hardware to get started. Each individual subnet requires its own router. For example, if you want to create 4 subnets, you’ll need 4 extra routers. The number of subnets you need depends on the size of your network and how much performance optimization you need. 

In subnetting, each individual subnet has its own unique network address. This process involves borrowing bits from the host portion of the IP address to create the subnet mask. Subnet masks help identify the network address and distinguish between the network and host portions of an IP address.

What Is a Subnet Mask?

A subnet mask is a 32-bit number that splits an IP address into a network address and a host address. A host address refers to a specific server or device on your network. 

To understand exactly what a subnet mask is, you need some background knowledge about IP addresses. An IP address is a string of numbers used to identify a computer or device on a network. 

Every IP address has 4 decimal numbers separated by periods. Each section is called an “octet.”  The number range for each octet is between 0 and 255. Just like your house address, devices and networks all have addresses so we can identify them. 

This makes communication possible. As an example, the first three octets in a default subnet mask for most home routers represent the network portion of the address and the last refers to the device or host address. This can differ depending on the size of the subnet. Every host (server or computer) on the network will have its own unique host address.

Subnet mask octets can be displayed with numbers between 0 and 255 or in binary form. For example, = 11111111.11111111.11111111.00000000

The 225 or 11111111 portion of the address is the network portion and the remaining part is the host portion. This helps reveal which parts of the address are for the network and which are for the device. 

Subnet masks are only used within an internal network and are not visible to the public. Every network, whether in a business or at home, already has a subnet mask. The only difference is its size.

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Benefits of Subnetting

Subnetting improves network design and management and is a handy tool for organizations with many devices on a network. Here are some of the top benefits of subnetting:

          • Easier administration. Subnetting ensures IP addresses are more organized and easier to troubleshoot or fix when problems occur.
          • Improved network performance. Dividing a network into smaller subnets lets you reduce broadcast traffic. Broadcasts are network messages sent to all devices, and when a network is congested with excessive broadcasts, it slows performance. 
          • Enhanced security. By isolating network segments into separate subnets, you can enforce more stringent access controls and deploy security measures in a more targeted way.

Subnetting can be a valuable strategy for network administrators. It lets you design and manage networks in a secure and scalable way.

Subnets vs Subnet Masks

Subnets and subnet masks might be related, but they’re not the same thing. Subnets are smaller separated networks that were originally part of a larger network. Subnet masks are strings of numbers used to differentiate between the network and host portion of an IP address. They are transformed versions of IP addresses within a subnet. You can’t create a subnet without a subnet mask.

How Do IPs and Subnet Classes Relate?

Let’s break it down in simple terms. IP addresses are like the individual postal addresses of devices on a network. We use them to locate and identify devices in a network. Contrastingly, subnet classes are like neighborhoods, and IP addresses are grouped or “classed” into specific ranges based on shared characteristics.

Subnet classes are ranges of IP addresses assigned to different subnets within a network. You might know that there are 3 primary subnet classes: Class A, Class B, and Class C. However, Class D and Class E also exist.

Each class can accommodate a specific range of IP addresses. Class A can host a large number of devices, Class B addresses are built for medium-sized networks, and Class C addresses are suitable for smaller networks. Subnet classes give a framework for us to manage and locate IP addresses. Subnet masks help us distinguish between network and host portions of an IP address within this framework. 

What Is the Default Subnet Mask for Class A, B, C, D, and E Networks?

Want to know the default subnet masks for all network classes? Default subnet masks provide a starting framework for network addressing. You can change subnet masks to make smaller subnets within a class, based on your network requirements. Here’s a run-down of the default subnet masks for all classes.

          • Class A. The default subnet mask is The first octet represents the network portion and the remaining 3 represent the host portion. Class A networks are usually used for large networks.
          • Class B. The default subnet mask for a Class B network is In this case, the first 2 octets indicate the network portion, and the remaining 2 octets represent the host portion. Class B networks are commonly used for medium-sized networks.
          • Class C. The subnet mask for a Class C network is The first 3 octets identify the network portion, and the last octet is the host portion. Class C networks work best with smaller networks.
          • Class D. Class D networks are for multicasting purposes and don’t use regular subnet masks. The IP addresses in Class D range between and In multicasting, data isn’t destined for a particular host but for the entire group of hosts that are part of that subnet.
          • Class E. Class E networks are also for special purposes and aren’t typically used for regular configurations. The IP addresses in Class E are between and

Can CyberGhost VPN Protect Your Subnet?

Yes, CyberGhost VPN can protect your network and all IP addresses within the subnet. Since each subnet will have its own router, you can configure CyberGhost VPN on each router to keep each subnet protected and private.

Organizations with large networks supporting many devices are particularly vulnerable to cybersecurity threats. For this reason, it’s even more important to keep networks protected and private. CyberGhost VPN offers many helpful security features to enhance your internet privacy and security. 

Global Server Network 

When you get a CyberGhost VPN subscription, you’ll get access to secure VPN servers worldwide. You’ll be able to choose IP addresses from countries of your choice and keep your real IP address and location masked. 

Having a large network at your disposal means you’ll always have access to a server with a strong connection. We’ll even automatically connect you to the best available server so you can start working without having to scroll through servers to find a good connection. 

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Connect to the best server in a single click

No Logs VPN

Unlike many VPNs on the market, we never track or log your activity. We adhere to a strict No Logs policy and RAM-only servers that can’t store your data. This means we can’t see what you’re up to when you connect to our VPN. To show we make good on our privacy claims, we invited Deloitte to independently audit our No Logs policy.

Our headquarters are located in privacy-friendly Bucharest, Romania which means we’re not mandated to keep information about people who use our services.  

Automatic Kill Switch 

If your internet connection suddenly drops and disconnects from the VPN, it could leave your real IP address and location temporarily exposed. Our Automatic Kill Switch keeps you protected even when your connection drops. We’ll stop incoming and outgoing traffic to your computer until you re-establish a connection to our VPN. 

Best Gaming VPN

Subnets are often used for gaming but even when you’re only gaming on a single device, you’re still vulnerable to spying and DDoS attacks. 

Keep your device or subnet safe with the best gaming VPN. You can also lower your ping by connecting to our VPN if your high ping rate is caused by content-based throttling.  

Unbreakable Encryption

Our military-grade encryption also prevents data leaks and scrambles your data beyond comprehension. Even if your data falls into the wrong hands, it would be impossible for anybody to interpret it. Get CyberGhost VPN.

Keep Your Subnets Safe

If you came here wondering “What is subnetting?” or “What is a subnet mask?” then hopefully, you got your answers. Too many devices on a single network can cause sluggish performance.

When your organization relies upon fast computer connections to function, slow-moving communication won’t cut it. By dividing a larger network into smaller, more manageable networks, you can enhance productivity and security. Keep your subnets safe by using a high-grade VPN to mask your location and encrypt your internet traffic. Get CyberGhost VPN to enhance your digital security toolkit.


What is a subnet mask and why is it used?

A subnet mask is a string of numbers used in subnetting to help you distinguish between the network and host portion of an IP address. The network portion refers to the shared address encompassing all devices on a subnet. The host portion refers to the individual devices on the subnet. 

What does the subnet mask 255.255 255.0 mean?

In the subnet mask, the first 3 octets (24 bits) of the subnet mask refer to the network portion. The remaining octet refers to the host portion. The subnet in question is a Class C subnet which is considered a small network. Find out more about subnet classes.

What is a subnet mask in simple terms?

In simple terms, a subnet mask is a bunch of numbers that help you know how large a subnet is. It does this by distinguishing between the network and host part of the address. The “255” part of subnet masks refers to the network portion and “0” refers to hosts or devices. 

For example, if the subnet mask is, you know it’s a large network since most of the address is for hosts. In contrast, if you have a subnet mask of, you know it’s a smaller network since only one octet is dedicated to devices. Get CyberGhost VPN to protect your subnets, routers, and devices.

What is your subnet mask?

A subnet mask is a set of numbers used in subnetting to separate the main network address from the individual device addresses. The network portion is the common address shared by all devices on the subnet and the host portion refers to the unique device addresses. Every subnet will have its own router and IP address. Find out how to check your router IP address in our helpful guide.

Can CyberGhost VPN protect a subnet?

Yes, absolutely! CyberGhost VPN is a great solution to safeguard your entire subnet. Our robust encryption protects your subnet from prying eyes and potential online threats. You can install CyberGhost VPN on your routers to keep your network traffic shielded by unbreakable encryption.

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