IP Addressing Series – Part 3: IPv4 Classes Explained with Examples

Understanding the concept of IPv4 classes in Networking – Easy Explanation

Introduction to IPv4 Classes

In networking, different networks have different sizes and requirements. To fulfill these requirements, IPv4 addresses are divided into different classes. These classes make network management easier and more organized.

The IPv4 classes are used to provide a suitable number of IP addresses for different networks. The IPv4 classes are divided into Class A, Class B, Class C, Class D, and Class E. Also, learn about networking basics, which helps you to understand IPv4 classes easily.

In today's blog, we will deeply learn all IPv4 classes in a detailed and beginner-friendly way. Before learning advanced topics of IPv4 classes, it is important to understand IPv4 in detail.

What Are IPv4 Classes?

IPv4 classes are different groups of IP addresses, these groups are used to manage networks easily.

The IPv4 classes are divide the IPv4 address space into different groups based on:

• The size of network
• The number of hosts
• Address ranges
• Network and host portions
• Usage purposes

There are five IPv4 classes used to manage different networks.

Every class has a different IP address range and used for different purposes.

• Class A
• Class B
• Class C
• Class D
• Class E

IPv4 classes used to organize IP addresses of different ranges.

Before learning IPv4 classes, one must learn about IP Addressing Fundamentals.

Uses of IPv4 Classes

Nowadays, the number of devices is increasing. Different organizations have various networking requirements, but a single addressing scheme is not suitable for all organizations. 

To solve this problem, IPv4 classes were introduced.

Different organizations require different sizes of networking, such as:

• Large companies or organizations require millions of host addresses
• Medium-sized networks are require in universities
• Small size networks are require in homes and offices

Thus, these size requirements can’t be fulfilled with a single address scheme, therefore IPv4 classes were introduced to separate networks according to requirements.

IPv4 classes help computer networks:

• Organize networks properly
• Efficiently manage IP addresses
• Supports small and large organizations
• Identify both network and host portions

Without IPv4 classes, the network management becomes very difficult.

Network and Host portions

Understanding the concept of network and host portions is important before learning IPv4 classes.

An IP address contains two parts:

• Network ID
• Host ID

The network part helps identify the network a device is part of, while the host part identifies a device within that network. 

In an IP address 192.168.16.25

• Network ID = 192.168.16
• Host ID = 25

Different IPv4 classes divide these portions differently.

Also, learn our guide on the TCP/IP model.

What is a subnet mask?

A subnet mask is a type of number used with an IP address to identify both the network part and host part.

For example:

• IP address: 192.168.2.26
• Subnet Mask: 255.255.255.0

In”192.168.2” the network part is indicated, and “26“is the host part. In subnet mask, “255” represents the network and “0” represents the host.

What are the Default Subnet Masks of IPv4 Classes?

The subnet mask helps figure out what is the network part and what is the host part of an IP address.

Class A IP Address

Class A IP addresses are for large networking. For example

• Internet companies
• Big organizations
• Multinational companies

Because they have to connect millions of devices.

The range of Class A IP addresses is from 1.0.0.0 to 126.255.255.255, Which means if the first octet of IP address is starts from 1 and ends at 126, then it becomes Class A IP address.

In Class A:

The first octet is network
The last 3 octets are hosts (devices)

For example 25.1.1.1

• 25 = network
• 1.1.1 = host

Subnet mask of Class A

255.0.0.0

• 255 = Network Part
• 0 = Host part

In Class A, only the first part is used for network and the remaining three parts are reserved for devices (hosts).

Therefore it supports millions of devices.

Class B IP Address

Class B IP addresses are used for medium-sized networks.
Which means large universities, medium companies, schools and regional offices.

The range of Class B IP addresses is from 128.0.0.0 to 191.255.255.255, Which means if the first octet of IP address is starts from 128 and ends at 191, then it becomes Class B IP address.

In Class B:

The first two octets are network
The Last two octets are hosts (devices)

For example 145.33.6.11

• 145.33 = network
• 6.11 = host

Subnet mask of Class B

255.255.0.0

• 255.255 = Network Part
• 0.0 = Host part

Class B supports a medium level number of devices.

Class C IP Address

A Class C IP address is used at home or in a small office. These are also good for networks and small businesses.

The range of Class C IP addresses is from 192.0.0.0 to 223.255.255.255, Which means if the first octet of IP address is starts from 192 and end at 223, then it becomes Class C IP address.

In Class C:

The first three octets are the network
The Last one octet is host (device)

Let’s Suppose IP address 192.168.5.17

• 192.168.5 = network
• 17 = host

Subnet mask of Class C

255.255.255.0

• 255.255.255 = Network Part
• 0 = Host part

Class C supports only a small number of devices because only one octet is available for hosts (devices).

Class D IP Address

Class D IP addresses are mainly used for multicasting, which means they are used for sending a message to lots of devices at the same time.

The range of Class D IP addresses is from 224.0.0.0 to 239.255.255.255, Which means if the first octet of IP address is starts from 224 and end at 239, then it becomes a Class D IP address.

In Class D:

There is no network or host part, it is used for group communication. Class D is used for this type of group communication.

Class D works:

One sender to many receivers, Class D IP addresses are used for live video streaming, online game servers, video conferencing etc.

Also, learn our previous guide on Network devices.

Class E IP Address

Class E IP addresses generally used for the Internet. These are reserved only for research or experimental purposes.

The range of Class E IP addresses is from 240.0.0.0 to 255.255.255.255, Which means if the first octet of IP address is starts from 240 and ends at 255, and it becomes a Class E IP address.

In Class E: 

There is no subnet mask and network or host part because this class is not designed for real networking.

This IP addresses used for research labs, experimental networking, and future protocol testing an advanced networking experiments.

What is the Difference Between IPv4 Classes?

This shows the exact differences between all IPv4 classes.

Private IP Address Ranges

Some IP addresses are reserved for private networking and not directly used on internet. They are used inside a local network such as homes, offices, and schools.

These IP addresses used for communication within a local network only, they are not used on the internet.

Class A Private Address Ranges

10.0.0.0 to 10.255.255.255 used for large private networks

Class B Private Address Ranges

172.16.0.0 to 172.31.255.255 used for medium-sized networks.

Class C Private Address Ranges

192.168.0.0 to 192.168.255.255 Class C IP addresses are the most commonly used range.

Real Life Example:

You can check in your home Wi-Fi:

• 192.168.1.1 will be your router
• 192.168.1.2 will be your mobile
• 192.168.1.3 will be your laptop

All of these are private IP addresses.

Advantages of IPv4 Classes

IPv4 classes provide multiple advantages in computer networking. Here are some major advantages of IPv4 classes:

• They provide easy organization of the network
• IP allocation in an efficient way
• Provide a good management for large and small networks
• Make communication easiest between devices
• Identifying the network and host portions of an IP address

This plays a major role in the development of the early internet.

Interview Questions to Remember

Define IPv4 Classes?

IPv4 classes are different groups of IP addresses, these groups used to manage networks easily.

Write all the names of IPv4 classes?

There are five main types of IPv4 classes:

• Class A
• Class B
• Class C
• Class D
• Class E

Tell the uses of Class A IP address?

Class A IP address is for large networking. For example

• Internet companies
• Big organizations
• Multinational companies

Because they are connecting millions of devices.

What is the range of Class A IP Address?

The range of class A IP address is from 1.0.0.0 to 126.255.255.255.

Tell the uses of class B IP Address?

Class B IP address is used for medium size networks.
Which means big universities, medium companies, schools and regional offices

What is the Range of Class B IP Address?

The range of class B IP address is from 128.0.0.0 to 191.255.255.255.

Tell the uses of Class C IP Address?

Class C IP address is used for small networks such as home network, local networks, small offices and businesses.

What is the Range of Class C IP Address?

The range of class C IP address is from 192.0.0.0 to 223.255.255.255.

Tell the uses of Class D IP Address?

Well it is basically a way of sending a message to devices all at the same time. The Class D IP address makes this possible allowing a message to be sent to devices simultaneously.

What is the Range of Class D IP Address?

The range of class D IP address is from 224.0.0.0 to 239.255.255.255.

Tell the uses of Class E IP Address?

Class E IP addresses are generally used for the internet. They are only reserved for research or experimental purposes.

Tell the default subnet mask of Class A, B and C IP addresses?

• Class A 255.0.0.0
• Class B 255.255.0.0
• Class C 255.255.255.0

Tell the one-line differences between Class A, B, and C?

• Class A IP addresses used for large networks
• Class B used for medium size networks
• Class C used for small networks

Define the network and host parts?

• The Network part is used to identify the network to which a device belongs to.
• The Host part is used to identify a specific device inside a network.

Tell the range of Private IP?

Class A private address ranges
10.0.0.0 to 10.255.255.255 used for large private networks

Class B private address ranges
172.16.0.0 to 172.31.255.255 used for medium sized networks.

Class C private address ranges
192.168.0.0 To 192.168.255.255 this is the most commonly used range of private IP

Why IPv4 classes were introduced?

In networking, different network have different sized and requirements, to fulfil these requirements IPv4 addresses divided into different classes.

Define multicasting?

Multicast is a way to send data from one device to devices at once. It helps to share data, with devices at the same time.
The data is sent from one source device to selected devices.

Which classes used for normal networking?

Class A, B and C are used for standard networking communication in networking while Class D and E are for tasks like multicasting communication or research purposes.

Why is class C used most commonly?

Class C IP addresses are used for small networks such as home networks, local networks, small offices and businesses. They provide enough IP addresses for local use.

Conclusion

IPv4 classes play an important role in computer networking by dividing IPv4 addresses into different categories based on network sizes and usage. Understanding of IPv4 classes is important because they are the foundation of computer networking and IP addresses.

In conclusion, Class A, B and C are used for standard networking communication in networking while Class D and E are for special purposes like multicasting communication or research purposes.

A Good understanding of IPv4 classes helps students grasp network organization, how IP address allocation, the basic of subnetting and network or host identification. These concepts are crucial before moving on to advanced topics in networking like IPv6, subnetting, VLSM, CIDR and routing.

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