At first glance, your IP address might look like a bunch of random numbers. However, there is a hidden logic behind this combination, and you don’t need to be a tech expert to crack it. It’s called a subnet mask, and if you’re wondering what a subnet mask is and how to find it, you’re in the right place.
There are millions of networks around the world, and they all vary in size. However, the larger a network is, the harder it is to manage and maintain. When a network is divided into smaller pieces, those pieces are called subnets. A subnet is a small network.
Subnetting is beneficial in many ways:
However, subnetting often requires additional hardware such as routers, so it also comes with a cost.
Just like every address is defined by a street name and a house number, an IP address consists of a network component and a host component. Let’s take 192.168.123.132 as an example. The first three octets (192.168.123.) represent the network and the last octet identifies a machine on your network.
IP addresses consist of 32 binary bits (4 x 8), but since they are long and complex, we use a dot decimal system.
192.168.123.132 = 11000000.10101000.01111011.10000100
The subnet mask reflects the network portion in an IP address. It might look look something this:
255.255.255.0 = 11111111.11111111.11111111.00000000
When you combine them, you get:
11000000.10101000.01111011.00000000 (network address: 192.168.123.0) 00000000.00000000.00000000.10000100 (host address: 000.000.000.132)
192.168.123.0 is your subnet, while 192.168.123.132 is a destination address (a device in your subnet). However, if you’re using a VPN, your IP will change depending on the server you’re connected to.
IP addresses are divided into three classes: A, B, and C. Classes D and E also exist, but they are not used by end users. Each class has a different default subnet mask, and you identify the class by looking at the first octet of an IP address. However, there are also different types of IP addresses: static, dynamic, public, and private.
Class A networks use a subnet mask of 255.0.0.0 and have 0-127 as their first octet. It allows 126 networks and almost 17 million hosts per network.
Class B uses a subnet mask of 255.255.0.0 and has 128-191 as its first octet. It is used by medium and large networks. Class B allows around 16,000 networks and 65,000 hosts per network.
Class C is used for local area networks (LAN) and allows 2 million networks with 254 hosts each. Class C uses a subnet mask of 255.255.255.0 and has 192-223 as its first octet.
Class D is reserved for multicasting (transmitting streaming media and other data for multiple users). It ranges from 224 to 239 and doesn't have a subnet mask as multicasting is not destined for a particular host.
Class E ranges from 240 to 255 and also doesn’t have a subnet mask. It is used for experimental and study purposes.
It’s worth noting, however, that the classful IP addressing is outdated. Classless Inter-Domain Routing, or CIDR, is a much more efficient way of allocating IP addresses.
Classless Inter-Domain Routing, or CIDR, was introduced in 1993 as a way to get rid of the classful network structure and significantly improve the method of allocating different IP addresses. It also aimed to reduce the stress across routing tables.
A routing table can be found in a router or some other network host. It’s essentially a table of rules and designations that tell a data packet which route it needs to take in a network to reach the desired location. Obviously, as IPv4 addresses spiraled out of control, routing tables needed to grow with them.
While originally planned as a temporary fix to stop the rapid exhaustion of IPv4 addresses, CIDR is still being used over twenty years later.
CIDR is based on variable-length subnet masking, or VLSM. Rather than using a mask to denote which IP address a network belongs to, a specific suffix can be combined with the IP address. This suffix contains the variable number of bits. This shortening of the display allows CIDR to create even more precise and numerous network divisions.
For example, here is a CIDR IP address:
The prefix is a standard IP address. The suffix (12) tells us how many bits the address has altogether.
The most important feature of CIDR is the ability to create supernets. This is done by combining CIDR blocks, groups of IP addresses with the same bits and network prefixes. By creating a supernet, an organization can reduce the stress on routing devices, while simultaneously saving address space.
The classful network structure eats up IPv4 addresses quickly. CIDR slowed the usage of IPv4 addresses down until the advent of IPv6 addresses, which would take a much longer time to deplete, if at all.
Subnet calculators give users a range of information: a subnet mask, network addresses, an IP class, usable host ranges, and more. There are different types of websites and apps designed to help manage your network and to allocate IP addresses to certain teams.
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Having your IP address publicly exposed is a risky business. It’s like driving around the city in a Ferrari with your home address written on the hood.
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When it comes to cybersecurity, it’s always best to stay ahead of the curve. Having a proactive attitude towards your online security will keep you a step ahead of any hackers or snoopers.