Home / Definitions / IPv4


Jenna Phipps
Last Updated May 24, 2021 8:02 am

Internet Protocol Version 4, known as IPv4, manages the transmission of communication between devices on a network through IP data packets. IP packets contain information that directs them from one IP address to another. IPv4 was initialized in the early 1980s.

Each device receives an IP address, which is either entirely unique or unique within its own network. IP addresses for IPv4 come in a series of numbers and periods; they can be up to 32 bits.

IPv4 and DNS

Though computer networks use IP addresses to communicate, human users would have a much more difficult time trying to pair devices and web servers with the appropriate lengthy IP address. The Internet‘s Domain Name System (DNS) provides a solution. Each IP address that belongs to a web server receives a domain name (for example, walmart.com). DNS servers record and cache IP addresses, and when an Internet user makes an IP request (such as loading a website), the DNS servers go through the process of retrieving the corresponding IP address.

IPv4 packet structure

IPv4 data packets have two different layers-the header layer (which contains fourteen different informational fields) and the data layer. The header fields contain data in bits and bytes and serve different functions within the packet. For example, the Total Length field lists how many bytes the IP packet has, and the Source and Destination Address fields indicate which IP address the packet is coming from and to which one it’s going. The header fields contain useful information about the packets that the computer can read and interpret. This information indicates how packets pass between networks, how long they live, and more.

The data layer contains the rest of the packet’s information.

IPv4, IPv6, and address protocols

When IPv4 was launched in the 1980s, Internet developers didn’t expect that so many IP addresses would be needed. But as more devices connected to the Internet in the 2000s, IP addresses began to run out. IPv4 addresses are only 32 bits long, which permits some billion number of addresses but certainly doesn’t allow for the numerous devices that now connect to the Internet.

IPv6 (version 6, the most recent Internet protocol adaptation) has been in development since the late 90s, but it wasn’t officially launched throughout the world until 2012. Its IP addresses are 128 bits long, which provides much more room for new devices. Both protocols are still used across Internet networks. Networks that are dual-stack support both IPv4 and IPv6. However, devices that support only one cannot communicate successfully with devices that only support the other.