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IPv4 vs IPv6: Definition, Differences, Pros & Cons Explained in 2025

IPv4 and IPv6 facilitate communication between connected devices. However, the two protocols differ in many ways, from adoption and address space to security and speed. Our IPv4 vs IPv6 guide explores these differences.

Samson KiarieSamuel ChapmanIgor Kurtz

Written by Samson Kiarie (Writer)

Reviewed by Samuel Chapman (Writer, Editor)

Facts checked by Igor Kurtz (Fact-checking editor)

Last Updated: 2024-11-13T16:49:14+00:00

All our content is written fully by humans; we do not publish AI writing. Learn more here.

IPv4 vs IPv6

Key Takeaways: IPv4 vs IPv6

  • IPv4 offers a limited address space of 4.3 billion possible IP addresses, whereas IPv6 provides 340 undecillion unique IP addresses. 
  • IPv4 has been powering internet communication since its early days, and nearly all devices support it. IPv6 is a newer version that’s compatible with a small but rapidly growing portion of internet and network devices. 
  • IPv4 supports unicast, multicast and broadcast addressing, while IPv6 offers unicast, multicast and anycast addressing methods. 

Facts & Expert Analysis About the Differences Between IPv6 vs IPv4:

  • Global IPv6 adoption: According to the latest data by the Asia Pacific Network Information Centre (APNIC), IPv6 adoption has grown from 8.82% in January 2017 to 36.44% in January 2024. 1
  • Core Protocol: Both IPv6 and IPv4 are different iterations of the Transmission Control Protocol/Internet Protocol suite, a communication standard that enables devices to exchange messages over a network.    
  • IPv6 has better routing efficiency: IPv6 allows networks to accommodate all address spaces with a small number of summary routes. This significantly reduces memory consumption and leads to better performance compared to IPv4. 

The Internet Protocol (IP) is responsible for enabling seamless communication between devices and servers across the globe. However, in order to communicate, the devices must be on the same IP version: either IPv4 or IPv6. In our IPv4 vs IPv6 guide, we’ll walk you through the features and functions of these two IPs to help you understand their differences.

IPv4’s simple virtual communication layer has been the backbone of the internet since its inception. It’s also a core offering of the best VPNs, so almost every internet device supports the IPv4 protocol. IPv6 is the newest IP version with solid security and faster speed, but its adoption rate has been slow, although it has sped up significantly in recent years. Read on to learn the finer distinctions.

  • 10/24/2024 Facts checked

    We updated the guide to add fresh details about IPv4 exhaustion and IPv6 adoption. 

IPv4 vs IPv6: Key Differences in a Table

The following table summarizes the key differences between IPv4 and IPv6: 

Details:IPv4IPv6
Address Length32-bit address128-bit address
Address FieldsNumerically based with 4 fields separated by periods (.)Alphanumerically based with 8 fields separated by colons (:)
Number of Octets4 octetsEach field has 2 octets, for a total of 16 octets
Address RepresentationIP address represented in decimal formatIP address represented in hexadecimal format
Address SpaceGenerates up to 4.3 billion unique addressesGenerates up to 340 undecillion unique addresses
IP ClassesOffers 5 IP address classes: Class A, Class B, Class C, Class D and Class EDoes not sort IP addresses into classes
Address ConfigurationSupports manual and DHCP configuration.Supports manual, DHCP and auto-configuration. Configuration depends on the system requirements.
Address ConfigurationSupports manual and DHCP configuration.Supports manual, DHCP and auto-configuration. Configuration depends on the system requirements.
Security FeaturesNo mandatory security measures. Security depends on the application.Uses Internet Protocol Security (IPsec) for security purposes. 
Encryption & AuthenticationNo encryption or authenticationProvides encryption and authentication
FragmentationForwarding routers and senders perform packet fragmentationOnly senders can perform packet fragmentation
Address TypesUnicast, multicast, broadcastUnicast, multicast, anycast
End-to-End Connection IntegrityNo end-to-end connection integritySupports end-to-end connection integrity

What Is IPv4?

An Internet Protocol version four (IPv4) address is a 32-bit IP address that provides the foundation of computer networks, offering features for internet communication. The protocol was first described in the Internet Engineering Task Force (IETF) publication (RFC 791), and the Defense Advanced Research Projects Agency (DARPA) developed it in late 1981.  

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IPv4 Address Format Example

IPv4 has two formats: a numerical format for the host’s reference and a binary format that the network device uses. The numerical format comprises four sets of numerals ranging from 0 to 255, separated by a period. 

All four sets in the numeric address have eight bits, which is why we refer to each set as an octet and an IPv4 address as a 32-bit integer. The numerical address is automatically converted to binary format so that internet and network devices can understand it. 

Pros and Cons of IPv4

IPv4 has its advantages and disadvantages, including the following points: 

Pros:

Cons:

What Is IPv6?

An Internet Protocol version six (IPv6) address is a 128-bit IP address that offers advanced features and a significantly larger address space. The new IP version was launched in June 2012, but its adoption has been sluggish. A Cloudflare study found that IPv6 accounted for 37% of all internet traffic at the end of October 2023. 

IPv6 Address Format Example

An IPv6 address has an alphanumeric and a binary format. The alphanumeric address is expressed in a hexadecimal format, comprising eight sets of alphanumeric characters separated by colons. Each set has 16 bits (two octets), which combine to make the 128-bit binary format of IPv6.  

Pros and Cons of IPv6

Here are some of the most notable advantages and disadvantages of IPv6: 

Pros:

Cons:

Difference Between IPv4 vs IPv6

The following are some key differences between IPv4 and IPv6: 

Address Space

We’ve already mentioned that IPv4 addresses are 32-bit, so there are only about 4.3 billion possible addresses. While that sounds like a lot, it won’t be enough to cover the ever-increasing number of network and internet devices. In fact, the five regional registries that allocate IPv4 addresses have either run out of supplies or are rationing them

The Internet Engineering Task Force (IETF) created IPv6 to manage the long-anticipated problem of IPv4 exhaustion. IPv6 offers a much larger address space; the addresses are 128-bit, providing a larger pool of over 340 undecillion combinations. 

To be precise, IPv6 offers 340,282,366,920,938,463,463,374,607,431,768,211,456 possible addresses. This unimaginably large number will provide enough capacity to satiate the next several generations.

Addressing Method

Both IPv4 and IPv6 support unicast and multicast addressing to identify machines connected to the network. IPv4 also offers broadcast addresses, whereas IPv6 supports anycast addresses. We’ll define these terms in this section.

IPv6 and VPNs

Most virtual private network (VPN) providers are built to assign addresses in IPv4. As the internet transitions to IPv6, providers must upgrade their infrastructure to support new addressing techniques.

However, since this upgrade is expensive and complex to undertake, only a few VPN providers have partially or fully migrated to IPv6, including all the entries on our best IPv6 VPN list. We’ll describe three of these standouts below:

Most of the best VPN providers have implemented IPv6 leak protection as a temporary solution. If you access a website that runs on IPv6 with one of these providers, the VPN will block IPv6 traffic to maintain your connection to the encrypted tunnel. See our NordVPN review and our ExpressVPN review to learn more about some top services that do this.

Without IPv6 leak protection, the VPN will redirect the request to an external IPv6 DNS server outside the VPN’s encrypted tunnel. This would leave you exposed, defeating the purpose of using a VPN in the first place. Since no major websites are currently running on IPv6 alone, blocking it altogether is still a viable solution, but this won’t be true forever.

When to Use IPv4 vs IPv6?

In theory, IPv6 is a better choice than IPv4 for many use cases because it’s faster and has fewer network address translation (NAT) issues. However, before you upgrade your router to IPv6, you must consider accessibility issues — only 37% of the internet supports IPv6 addresses. 

Which Is Better for Gaming: IPv4 or IPv6?

Theoretically, IPv6 is better for gaming than IPv4 as it offers faster and more reliable connections. However, the best option for you will depend on whether your devices, residential ISP and online games support IPv6. 

Which Has Better Speed: IPv4 or IPv6?

IPv6 is faster than IPv4. Along with having faster routing and packet processing, it doesn’t use network address translation.

Which Is More Secure: IPv4 or IPv6?

IPv6 is more secure than IPv4 thanks to its built-in security tools such as the IPsec protocol, which encrypts and authenticates packets. Other security features like router advertisement (RA) guard and Secure Neighbor Discovery (SEND) protect against rogue neighbor discovery and router advertisements, thus improving routing security. 

Final Thoughts: Which Is Better: IPv4 or IPv6? 

IPv6 is faster and more secure than IPv4, which makes it ideal for virtually any online activity. In addition, the new Internet Protocol offers an arbitrarily large pool of possible addresses to support the ever-increasing amount of network and internet devices. 

The only problem is that the present-day internet doesn’t have the infrastructure and network policies to support IPv6. Most devices and online resources still rely heavily on IPv4, contributing to the snail-paced adoption of IPv6. 

The VPN industry paints a picture of the current status of IPv4 vs IPv6 adoption patterns in the internet space. While some VPN providers are leading the charge regarding IPv6 adoption, the rest of the park is playing the waiting game — applying short-term solutions like IPv6 leak protection to safeguard user security.  

Do you think IPv6 is a better replacement for IPv4? Have you used an IPv4 VPN to access IPv6 websites? What challenges did you encounter? We’d like to hear about it in the comments section. As always, thanks for reading. 

FAQ: IPv6 vs IPv4

Sources:

  1. Use of IPv6 for World (XA) – Asia Pacific Network Information Centre

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