What is a Subnet Mask?

February 22, 2022 By Janne Smith No Comments 7 minutes

A subnet mask divides the network into smaller chunks, i.e., subnetworks. All your internet devices have a subnet mask, but finding it depends on your use. And, that’s all this article is about. In this blog post, we’ll briefly walk you through what is subnet mask, how to find subnet mask on different devices, a comparison of it with an IP address, and wrap up with the FAQs. Let’s dive in!

What is Subnet Mask

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What Is a Subnet Mask?

Every telephone has a different contact address, which you get when you register for a landline. The same is true with IP addresses. Every device has a different IP address, which consists of two components: the host and the network component.

Here’s an example to explain what is subnet mask. You’ve got 000.000.000.000 as an address. Decimals separate the first three sets; 000.000.000 represents the network, while the last set (000) represents the machine on the network.

All IP addresses are 32 bits; remembering or copying the same set can be confusing. Therefore, all addresses are divided into bits to avoid confusion. Overall, the address is in a set of 4×8, making it into 32 binary bits.

Here’s an illustration of examples of what is subnet mask:

IP address: 192.168.1.100

Subnet Mask: 255.255.255.0

The Subnetmask portion represents the network address, and combining the IP address and the Subnetmask results in a long pattern of binary digits. Moreover, connecting to the VPN will change your IP address depending on the server’s location.

How Does A Subnet Work?

Now that you know what is subnet mask, here’s all about how it works. Subnetting is important because it allows a network to be broken down into smaller networks. The easiest example is that a router connected through another router is different from the primary network. It’s why disabling double NAT works in favor of inbound traffic.

Wide Area Network (WAN) does not cater to the information regarding the host address. It only knows which network the host is a part of and forwards data to the correct network, which is directed to the correct host on the subnet.

Subnet Mask vs IP Address

It’s never easy to understand networking complications. And if the previous section about what is subnet mask has got you scratching your head when trying to understand the differences between a subnet mask and an IP address, we’ve got your back!

Here’s a brief comparison of Subnet Mask vs IP address to clear the air about what is subnet mask:

Feature	IP Address	Subnet Mask
Purpose	Uniquely identifies a device on a network.	Explains an IP address’ network portion.
Format	IPv4: Four octets in dotted decimal. IPv6: 8 groups of 4 hexadecimal digits separated by colons.	32-bit number in dotted decimal
Components	Network address and host address	Network bits and host bits
Function	Identifies individual devices	Determines network boundaries and available hosts
Role in Network Communication	Used for addressing data packets	Used for routing data packets to the correct network

How to Find Subnet Mask From IP Address

With the IP address vs Subnet mask briefly explained, here’s how to find subnet mask from an IP address on different devices:

Find Subnet Mask on Android

Here’s how to find subnet mask on Android:

Go to Settings > Wireless & Networks > WiFi.
Select the connected Network.

You can now see the subnet mask and additional network information.

Find Subnet Mask on iOS.

Here’s how to find subnet mask on iOS:

Go to Settings > WiFi.
Select the connected Network.
Tap on “i”.

You can now see all network details.

Find Subnet Mask on Windows

Here’s how to find subnet mask on Windows:

Use the search bar.
Navigate and open the Control Panel.
Go to the Network and Sharing Centre.
Select the connected network > Advanced.
Select your TCP/IP.

You can now see your IP address and the sub net mask.

Find Subnet Mask on Mac

Here’s how to find Subnet Mask on your Mac device:

Press the space bar + Command keys together.
Navigate and go to System Preferences > Network.
Choose your Network > Advanced.
Select TCP/IP.

You can now see your IP address with the sub net mask.

What Are the Different Parts of the IP Address?

Note: The traditional class-based IP addressing system is now considered outdated. Classless Inter-Domain Routing (CIDR) has become the preferred method for more efficiently allocating IP addresses.

All IP addresses are divided into 3 categories: A, B, C, D, and E. However, the users don’t use the last two classes. Moreover, all IP address classes have their specific default Subnetmask. Here are the 4 classes briefly described:

Class A

These use a sub net mask 255.0.0.0 and have a first octet ranging from 0 to 127. This class supports 126 networks, with each network accommodating nearly 17 million hosts.

Class B

This class of networks is characterized by a sub net mask of 255.255.0.0 and a first octet between 128 and 191. It suits medium to large networks, offering approximately 16,000 and 65,000 hosts per network.

Class C

This class is typically used for local area networks (LANs). Its sub net mask is 255.255.255.0, and its first octet ranges from 192 to 223. This class supports about 2 million networks, each with up to 254 hosts.

Class D

Class D addresses, spanning from 224 to 239, are reserved for multicasting, which simultaneously sends data streams to multiple users. They do not use a Subnetmask, as multicasting is not intended for specific hosts.

Class E

This network class covers the range from 240 to 255 and is not assigned a Subnetmask. It is designated for experimental and research purposes.

What Is a Subnet Mask Calculator?

Subnet calculators provide essential information such as subnet masks, network addresses, IP class details, and the range of usable hosts. Various tools and applications are designed to help manage and allocate IP addresses within a network.

A subnet range calculator gives you the beginning and ending addresses of a subnet. An IPv4 to IPv6 converter facilitates the conversion of IP addresses from IPv4 format to IPv6 format.

Subnet mask calculators reveal available subnets along with their subnet masks. Additionally, an IPv4 CIDR calculator lets you enter a subnet range and view detailed IP address information for that range.

What Is a Subnet Mask Cheat Sheet?

A sub net mask cheat sheet assists administrators in swiftly identifying the location of an IP address within a subnet by using both the IP address and the sub net mask. Subnet masks are utilized to split an IP address into two sections: the network and the host.

The subnet mask mirrors the IP address in length, with bits for the network portion set to 1s and bits for the host portion set to 0s. Additionally, the subnet mask can be expressed by the number of bits allocated to the network part; for instance, if there are 27 bits in the network segment, the subnet mask is denoted as /27.

FAQs - What is a Subnet Mask?

What is my IP address and subnet mask?

An IP address consists of 32 bits, organized into 4bytes, each containing 8 bits. Moreover, every TCP/IP network device, such as computers, printers, routers, and switches, is assigned a unique IP address. A sub net mask separates IP addresses into network and host components, enhancing network performance and security.

How to subnet an IP address?

To subnet an IP address, define the required subnets and hosts. Adjust the Subnetmask to match these needs by extending the network bits. For example, changing from /24 to /27 creates smaller subnets. Determine the ranges for each subnet and allocate IP addresses. Furthermore, check the results to confirm correctness.

What is subnet mask and why it is used?

A Subnetmask splits an IP address into two segments: one that specifies the host (such as a computer) and another that designates the network to which it is connected.

What is a subnet mask in simple terms?

A subnet is a 32-bit value dividing an IP address into network and host portions. Moreover, routers utilize subnet masks to direct data packets to the appropriate subnet within a network.

What are 2 types of subnet?

There are two main types of subnetting: Fixed-Length Subnet Mask (FLSM) and Variable-Length Subnet Mask (VLSM). FLSM involves creating subnets with equal host addresses and using the same sub net mask for all. However, VLSM allows for subnets with varying numbers of host addresses, each with a different Subnetmask.

Conclusion

You might now understand a subnet and why it’s important for networking. Subnets also help slow down the exhaustion of IPv4 addresses. Like IPv4 networks, IPv6 networks have prefixes. We recommend reading about the differences between IPv4 and IPv6 in our blog.