IP Address Classes Tutorial


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In this IP Address Classes Tutorial, we’ll learn about the IP address and the ways it underpins all network communication. We’ll also see how to use Python’s ipaddress module to view and manipulate IP addresses in Python.

In the past, TCP/IP divided IP addresses into five different categories called classes. Each class defined a certain number of bits for its network prefix and host address.

Class A

The IP Address Classes Tutorial is an essential concept for any DevOps engineer or developer to understand. IP addresses are a key part of any networking environment, especially when it comes to cloud and Kubernetes. Understanding how addresses work in binary format can make your life easier when it comes to using network protocols and managing subnets.

The first octet of an IP address determines the class of the IP address. Each octet contains one to four bits that can be either ON or OFF depending on the class. The first bit in a Class A address is always zero, while the other three bits can be either ON or OFF.

Class A addresses are used for large networks. This class of IP addresses supports 16 million hosts on each of 127 networks, which is why they are sometimes called big-network addresses.

You can think of the first octet in an A-class address as the first bit that identifies the network, and the remaining three bits as the host bits. The number of host bits varies from class to class, but the first 24 bits are reserved for the network address and the last 8 bits are available for the host address in each class of IP addresses.

In addition to the network address and the host address, IP addresses can also be divided into two other parts: the network addressing component and the device identifying component. The network addressing component is what all the devices on a computer network use to identify themselves.

The network addressing component of an IP address also contains the subnet mask that is used to divide the IP address into subnets. The subnet mask consists of four bits that are assigned to each device on the network based on its device identifying component.

Class B

IP addresses are a type of number used to identify computers on an Internet Protocol network. Each IP address has a prefix, which identifies the physical network, and a suffix, which identifies the individual host.

In order to assign Internet IP addresses, it is important to understand the IP Address Classes system. There are five IP address classes: Class A, Class B, Class C, Class D, and Class E.

Class A is the largest and most commonly used network class. All addresses in this class have the two most significant bits set to 0 and the network number is given by the next seven bits. This means that the total number of addresses in this class is 128.

The next largest class, Class B, contains all addresses with the most significant bit set to 1. The network number is given by the next 14 bits, leaving 16 bits for numbering hosts on the network. This gives a maximum of 65536 hosts per class B network.

While the Class A, B, and C networks can accommodate millions of hosts, Class D addresses are limited to a single block of IP address space, while class E addresses are reserved for research and development purposes. This creates a problem for organizations that want to provide their employees with IP addresses.

As the Internet becomes more and more common, the demand for IP addresses increases. This is why the Internet Protocol hierarchy has several IP address classes to help organizations efficiently allocate addresses and provide the best network performance possible.

To make the most of the available addressing space, each IP address is divided into network and host parts. The first octet of each IP address is dedicated to network part and the remaining four octets are dedicated to host part. This is called subnetting. Host bits are also flexible and can be adjusted by administrators to meet the requirements of their networks.

Class C

Class C is a type of IP address that is used for small networks. These types of networks are generally located at home, offices, or schools. This type of network consists of three octets that are used to indent the IP range between 192 and 223.

The first two bits of a Class C IP address determine the network portion of the address, while the last bit is used as the host portion. The network portion identifies the subnet, and the host portion identifies the individual hosts. The network portion of the IP address is usually represented by 1s, while the host portion is typically represented by 0s.

Another important part of the IP address is the subnet mask. Each network has a unique subnet mask that helps routers pass information across the network. This allows packets to be sent from one network to the next without having to know the exact address for each host.

This can save a lot of addressing space for the network, as well as help routers send packets to the correct host. The subnet mask is often written as a string of ‘1’ that starts from the left side and continues without interruptions.

The subnet mask for a Class C IP address is usually ‘’ This is a bit more complicated than the other masks. The mask has to specify how many host-number bits are in the network portion of the address. The mask can contain a maximum of 224 host-number bits for Class A addresses, 216 for Class B addresses, and 28 for Class C addresses.

When you learn about the different classes of IP addresses, you can make better decisions about the IP addressing strategy for your network. This is especially important when you’re building a new network and deciding how to divide it up into smaller subnets that will allow easier management.

Class D

An IP address is an eight-bit address that identifies a device on a network. The address can be written in either dotted decimal or binary notation. It is a fundamental concept that every DevOps engineer or developer should know.

To make the system easier to understand, IP addresses are divided into different classes based on the order of bits in the first octet. Each class has a range of valid IP addresses.

The class A address is the most commonly used, and it is usually assigned to commercial devices such as laptops, routers, and firewalls. It also has a small range of reserved private addresses that are used in closed networks and are not routable on the public Internet.

Another important class is Class B. This is a smaller class than Class A, and it is generally used by small local area networks (LANs).

In class B, the first octet is 128 to 191 in decimal notation, which means that all bits between those points are set to zero. The second octet is a zero, and the remaining octet is an address.

This type of IP addressing is useful for small networks and can be found on most home routers. The first 24 bits of the IP address are dedicated to the network, and the last three are dedicated to the host.

The second level of IP addressing is host addressing. Each host has a unique network address and a host address. Host bits are flexible, and administrators can use them as network bits to maximize the number of host addresses available in a network.

Class E

IP addresses are a group of numbers separated by dots that identify networks and hosts on them. Each number in an address is called an octet and consists of 8 bits. The first bit of an octet is the network identifier, while the rest are used to identify hosts.

Each octet contains four parts: the first part is called the prefix, the second is called the host identifier, and the third is called the subnet mask. The prefix part identifies the physical network to which the computer is connected, while the host identifier part identifies the individual host on the network.

There are 5 classes of IP addresses defined by TCP/IP: Class A, B, C, D and E. Each class has a range of valid IP addresses based on the value of the first octet.

Class A addresses occupy half of the available IP addressing space and are used for networks with large numbers of total hosts. The first octet of a Class A network number, is the Network ID, and the remaining three octets are used to identify the host identifier.

This class can accommodate 126 networks, and each of these can support a maximum of 17 million hosts. This class is also used to define private networks and loop addresses for specialized uses.

Another benefit of this class is that it takes up a fraction of the address space, as opposed to Class A and B which use all available addressing space for network traffic. It is therefore often used for experimental and research purposes, such as testing new protocols.

A Class E address, on the other hand, is not used for network traffic, but instead, it is reserved for use in research and development. It also uses a smaller portion of available addressing space than Class A, B and C.

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