What is IPv4 (Internet Protocol version 4)?

What is an IP address?

An IP address, also known as an Internet Protocol address, is a unique numerical identifier assigned to each device connected to a computer network. It serves as a way to identify and locate devices on a network. IP addresses play a crucial role in facilitating data transfer across the internet. They enable devices to find and communicate with each other, ensuring that your requests reach their intended destinations.

Learn more What is the IP (Internet Protocol)?


What is IPv4?

IPv4, or Internet Protocol version 4, is the fourth version of the Internet Protocol. It is the most widely used protocol for Internet communication. IPv4 uses a 32-bit address scheme, allowing for approximately 4.3 billion unique addresses. IPv4’s enduring popularity is a testament to its effectiveness. Despite newer versions, a significant portion of the internet still relies on IPv4 for connectivity.

How does IPv4 Work?

IPv4 is a crucial component of the TCP/IP suite of protocols. To put it briefly, TCP/IP is the protocol that makes it possible for electronic gadgets to exchange data over the Internet.

IPv4 works by dividing the 32-bit address into four sections, each separated by a dot. Each section can range from 0 to 255, representing a total of 256 possible values. This allows for a wide range of unique addresses.

IPv4’s job is to assign numerical identifiers to computers, known as IPv4 addresses, and to route information between them via the Internet. IPv4 thereby allows for the unique identification of hosts over an IP network. Nonetheless, keep in mind that IPv4 relies on best-effort delivery. This signifies that the protocol will attempt delivery to the host, but there is no certainty that it will succeed. IPv4 uses “IP addresses,” which are actually 32-bit logical addresses.


Benefits of using Internet Protocol version 4

  • Compatibility: IPv4 is universally supported and recognized across the internet. Nearly all devices, routers, and networking equipment are compatible with IPv4, ensuring seamless connectivity.
  • Familiarity: IPv4 is well-established and familiar to network administrators, making it easier to configure and manage compared to newer protocols.
  • Widespread Adoption: The vast majority of internet services and websites still use IPv4. This widespread adoption means that IPv4 remains the primary means of communication for most internet users.
  • Backward Compatibility: IPv4 can coexist with IPv6, allowing for a gradual transition to the newer protocol. This backward compatibility ensures that existing IPv4 services continue to function as IPv6 adoption increases.
  • Simplicity: IPv4 addresses are relatively straightforward, consisting of four sets of numbers separated by periods (e.g., This simplicity makes it accessible to a wide range of users and devices.

IPv4 Classification

IPv4 addresses can be classified into five different classes: A, B, C, D, and E. Classes A, B, and C are used for general addressing purposes, while class D is reserved for multicast addresses, and class E is reserved for experimental purposes.

ClassAddress RangeDefault Subnet MaskNumber of Hosts
Class A1.0.0.0 – 16 million
Class B128.0.0.0 – 65,000
Class C192.0.0.0 – 254
Class D224.0.0.0 – applicableReserved for multicast groups
Class E240.0.0.0 – applicableReserved for experimental use
ipv4 address format

IPv4 Addressing Modes

IPv4 supports three addressing modes: unicast, multicast, and broadcast. Unicast is used for one-to-one communication, multicast is used for one-to-many communication, and broadcast is used for one-to-all communication.

  1. Unicast Addressing: The most popular mode in IPv4 is unicast addressing. In this method, data goes from a single sender to a single receiver. Each object on a network is given a unique IPv4 address, which makes it possible to send data exactly where it needs to go. It’s like sending a personal letter to the home address of a certain person.
  2. Broadcast Addressing: The opposite of broadcast addressing is unicast. In this method, data is sent from one sender to all devices in a certain network segment. The sender uses a special broadcast address to make sure that every device on that section gets the message. Think of it like making a speech in a room full of people where everyone can hear it.
  3. Multicast Addressing: This is a middle ground between unicast and broadcast. In this method, information is sent from one sender to a small group of interested recipients. Devices that want to get multicast traffic sign up for certain multicast group addresses. This mode is great for streaming material or sending data to a small group of devices on a network, such as in a group video call where only the people on the call can see the video stream.

Parts of IPv4

An IPv4 address consists of two main parts: the network address and the host address. The network address identifies the network to which the device belongs, while the host address identifies the specific device on the network.

IPv4 addresses, like, consist of four groups of integers separated by periods. There are an enormous amount of possible permutations because each set has a range of 0-255. The IPv4 address consists of the following four groups:

  • Network Address: The initial sets of numbers (e.g., 192.168) typically represent the network portion of the address. This section is used by routers and switches to figure out which network the data packets are destined for.
  • Subnet Address: In some cases, the address may include a subnet portion (e.g., 192.168.0). Subnetting is a method used by system administrators to partition a larger network into more manageable chunks, typically for reasons of security or performance enhancement.
  • Host Address: The last set of numbers (e.g., represents the host portion. It’s a way to single out a particular piece of hardware or computer system on a network. This section is used by data packets to identify the particular network node at which they will be received.

Advantages and Disadvantages of IPv4

Advantages of IPv4

  1. Familiarity: IPv4 is deeply entrenched in the Internet infrastructure, making it easily recognizable and compatible.
  2. Widespread Adoption: The vast majority of devices and networks currently use IPv4, ensuring global connectivity.
  3. Backward Compatibility: IPv4 can coexist with IPv6, allowing for a smooth transition.

Disadvantages of IPv4

  1. Address Exhaustion: The limited address space of IPv4 has led to address exhaustion, making it challenging to allocate new addresses.
  2. Security Concerns: IPv4 lacks built-in security features, leaving networks vulnerable to cyber threats.
  3. Inefficient Routing: Its routing mechanism can result in inefficient data transmission.

Why IPv6 over IPv4?

IPv6 is preferred over IPv4 because it overcomes the shortcomings of the former, most notably the problem of address exhaustion, while also providing better security, more efficient routing, and the ability to accommodate an ever-increasing number of internet-connected devices and services. IPv6 delivers a stable and scalable groundwork for the Internet’s further evolution and expansion.

The most pressing issue with IPv4 is the exhaustion of its 32-bit address space. With the rapid expansion of the internet and the increasing number of connected devices (including smartphones, IoT devices, and more), there simply aren’t enough unique IPv4 addresses to accommodate them all. IPv6, with its 128-bit address space, provides an abundance of unique addresses, ensuring that address exhaustion is not a concern.

IPv6 incorporates enhanced security features compared to IPv4. It includes built-in support for IPsec (Internet Protocol Security), which offers encryption, authentication, and data integrity, addressing some of the security vulnerabilities associated with IPv4.

Address Length32 bits128 bits
Address NotationDotted Decimal (e.g., Colon (e.g., 2001:0db8:85a3:0000:0000:8a2e:0370:7334)
Address SpaceLimited (4.3 billion addresses)Vast (Approximately 340 undecillion addresses)
Header LengthFixed (20 bytes)Variable (Minimum 40 bytes)
Header ComplexitySimplerMore Complex
Header FieldsFewerMore
Security FeaturesOptional (IPsec add-on)Built-in (IPsec)
NAT (Network Address Translation)CommonNot Required (Due to ample addresses)
Routing EfficiencyLess Efficient due to NATMore Efficient (Simplified Routing)
BroadcastSupportedNot Supported
MulticastLimited SupportRobust Support
Auto-ConfigurationRequires DHCP for dynamic addressingBuilt-in (Stateless Autoconfiguration)
FragmentationRouters and hosts both perform fragmentationRouters perform fragmentation
Transition MechanismsVarious mechanisms needed for IPv4 to IPv6 transitionCoexistence mechanisms for IPv4 and IPv6
Usage StatusWidely used, but facing address exhaustionIncreasing adoption, future-proofing

It’s worth noting that while IPv4 continues to be widely used, the limitations of its address space are driving the gradual transition to IPv6. IPv6 offers a more extensive address pool, improved security features, and better support for the growing number of devices and services connected to the internet. Organizations are encouraged to plan for IPv6 adoption to ensure long-term scalability and sustainability in the digital age.

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