What is a Subnet Mask?
date
Sep 27, 2022
slug
what-is-a-subnet-mask
status
Published
summary
Subnet Mask is a tool that is used for spliting network into subnetworks. Learn the details about subnet mask and how to find it on different devices.
tags
Website
type
Post
featured_image_url
Author
Dilara Yavuz
category
Privacy & Security
meta_title
What is a Subnet Mask? How Do You Find Subnet Mask? - FastVPN
A subnet mask is a tool used in networking to split a network into smaller subnetworks. It does this by assigning a network address to each device on the network and specifying which bits in the address identify the network and which identify the host. The subnet mask allows devices on different networks to communicate with each other while preserving their individual addresses. Without a subnet mask, large networks would be incredibly difficult to manage, and devices would be unable to reach hosts on other networks.
What is a Subnet Mask Explained?What are the different classes of IP addresses?Class AClass BClass CClass DClass E1. Private IP2. Public IPHow do you find the subnet mask?On WindowsOn a MacOn a RouterOn iOSOn AndroidOn LinuxWhat is a subnet mask calculator?Subnet mask cheat sheetWhy should I hide my IP address?Proxy ServerUse of VPNAnonymity networkHistory
What is a Subnet Mask Explained?
The subnet mask is used to divide a network into smaller subnetworks, or subnets. The subnet mask specifies which bits in the IP address identify the network and which bits identify the host. This allows devices on different subnets to communicate with each other while preserving their individual addresses.
The subnet mask is usually written in quad-dotted decimal notation, such as 255.255.255.0, which means that the first 24 bits of the IP address are used for the network and the last 8 bits are used for the host.
Subnetting is a way to increase the efficiency of IP address space by dividing a large network into smaller subnets. This allows organizations to use their IP addresses more efficiently and helps to reduce the number of broadcast domains.
Without a subnet mask, large networks would be incredibly difficult to manage and devices would be unable to reach hosts on other networks. Meanwhile, a subnet mask is an essential tool for network administrators.
IP addresses are divided into two parts:
Network part: The network part identifies the network where the host is located.
Host part: The host part identifies the specific device within that network.
What are the different classes of IP addresses?
The different classes of IP addresses have different ranges of values. IP addresses are divided into five classes: A, B, C, D, and E.
Class A
Class A addresses are used for large networks. The first octet is the network portion, and the last three octets are the host portion. The first bit is always set to 0, and the last bit is always set to 1. This class of addresses includes all IP addresses that start with 0, 1, 2, 3, 4, 5, 6, 7, 8, or 9.
Class A address can have any value from 1 to 126 in the first octet. The class of an IP address can be determined by looking at the first octet of the address. Moreover, If the first octet is between 1 and 126, it is a class A address. This Class address has 8 bits for the network and 24 bits for the host.
Class B
Class B addresses are used for medium-sized networks. The first two octets are the network portion, and the last two octets are the host portion. The first bit is always set to 1, and the second bit is always set to 0. This class of addresses includes all IP addresses that start with 10, 11, 12, 13, 14, 15, or 16. Moreover, If the first octet is between 128 and 191, it is a class B address.
Class C
Class C addresses are used for small networks. The first three octets are the network portion, and the last octet is the host portion. The first bit is always set to 1, the second bit is always set to 1, and the third bit is always set to 0. This class of address includes all IP addresses that start with a 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28 or 29. Moreover, the class C address has 24 bits for the network and 8 bits for the host. If the first octet is between 192 and 223, it is a class C address.
Class D
Class D addresses are used for multicast groups. The first four octets are the network portion, and the last octet is set to 1. The first bit is always set to 1, the second bit is always set to 1, the third bit is always set to 1, and the fourth bit is always set to 0. This class of addresses includes all IP addresses that start with 30, 31, 32, 33, 34, 35, 36, 37, 38, or 39. Moreover, If the first octet is between 224 and 239, it is a class D address.
Class E
Class E addresses are reserved for future use. The first four octets are the network portion, and the last octet is set to 1. The first bit is always set to 1, the second bit is always set to 1, the third bit is always set to 1, and the fourth bit is always set to 1. This class of addresses includes all IP addresses that start with 40, 41, 42, 43, 44, 45, 46, 47, 48, or 49. Moreover, If the first octet is between 240 and 255, it is a class E address.
IP addresses are further divided into subclasses based on their purpose. For example, there are private IP addresses and public IP addresses.
1. Private IP
Private IP addresses are used for devices that are not connected to the Internet, such as computers on a local network.
2. Public IP
Public IP addresses are used for devices that are connected to the Internet, such as servers.
Subclasses can also be created for specific types of networks. For example, there is a subclass of IP addresses that are used for point-to-point links.
How do you find the subnet mask?
To find the subnet mask on different devices, you will need to look in different places. So, here are some of the ways you can find the subnet mask on different devices.
On Windows
- Open the Network and Sharing Center
- Click on Change adapter settings
- Right-click on your active network connection and select Properties
- Select the Internet Protocol Version 4 (TCP/IPv4) option and click the Properties button
- In the Properties window, you will see your IPv4 address and your subnet mask.
On a Mac
- Open the System Preferences
- Click on Network
- Select your active network connection and click the Advanced button
- In the Advanced window, you will see your IPv4 address and your subnet mask.
On a Router
- Look at the router’s IP address
- The subnet mask will be listed next to the IP address.
On iOS
- Go to Settings > WiFi
- Select the network you want to connect
- Tap the info button next to the network name
- You will see your IPv4 address and your subnet mask.
On Android
- Go to Settings > WiFi
- Select the network you want to connect
- Tap the gear icon next to the network name
- You will see your IPv4 address and your subnet mask.
On Linux
- Open the terminal and type “ifconfig”
- Find the interface that is connected to the network you are in
- Look for the “inet addr” and “netmask” fields. The “inet addr” will be your IPv4 address and the “netmask” will be your subnet mask.
What is a subnet mask calculator?
A subnet mask calculator is a tool that helps one calculate the appropriate subnet mask for a given IP address. It takes the dotted decimal notation of an IP address and performs a bit-wise AND operation with the given subnet mask. The resultant marked IP address is then used to identify the network to which the IP address belongs.
Subnet mask cheat sheet
A subnet mask cheat sheet is a handy tool that network administrators can use to quickly find the appropriate subnet mask for a given IP address. This cheat sheet provides a quick reference for finding the right subnet mask for each IP address class (A, B, C, D, and E). It also includes information on special cases, such as broadcast addresses and private addresses. With this cheat sheet, you can quickly find the subnet mask that you need, without having to memorize a lot of complicated information.
Why should I hide my IP address?
There are a number of reasons why you might want to keep your IP address hidden. Perhaps you’re worried about online privacy or maybe you want to access websites or content that is blocked in your country. Whatever the reason, there are a few different ways to hide your IP address.
Proxy Server
One way is to use a proxy server. A proxy server is basically a middleman between your computer and the internet. When you connect to a website through a proxy, the website will see the IP address of the proxy server instead of your own. There are both free and paid proxy services available.
Use of VPN
Another way to hide your IP address is to use a virtual private network (VPN). A VPN encrypts all of the traffic between your computer and the VPN server, making it impossible for anyone to see what you’re doing online. Again, there are both free and paid VPN services available.
Anonymity network
Finally, you can use Tor, which is a free anonymity network that routes your traffic through multiple volunteer computers around the world, making it very difficult to trace back to your original IP address.
Moreover, whichever method you choose, hiding your IP address is a good way to protect your online privacy and access blocked content.
History
IP address classes were originally defined in 1981 by the Internet Engineering Task Force (IETF) in RFC 790. The purpose of defining different classes was to help conserve address space at a time when the number of available IP addresses was limited.
With the introduction of Classless Inter-Domain Routing (CIDR) in 1993. The need for IP address classes was eliminated. CIDR allows for a more flexible allocation of IP addresses and eliminates the need for address classes.
Even though, there is no need for IP address classes. But still used in some network devices and applications. For example, many routers use classful routing protocols such as Border Gateway Protocol (BGP) that require the use of IP address classes.
The use of IP address classes also continues in some documentation and tools. For example, the ping command uses the -c option to specify the number of packets to send, where c is a number between 0 and 255. Therefore, this option is called the Classful Ping Option and it is used to test connectivity to hosts on different networks.
