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.
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.
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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: | IPv4 | IPv6 |
---|---|---|
Address Length | 32-bit address | 128-bit address |
Address Fields | Numerically based with 4 fields separated by periods (.) | Alphanumerically based with 8 fields separated by colons (:) |
Number of Octets | 4 octets | Each field has 2 octets, for a total of 16 octets |
Address Representation | IP address represented in decimal format | IP address represented in hexadecimal format |
Address Space | Generates up to 4.3 billion unique addresses | Generates up to 340 undecillion unique addresses |
IP Classes | Offers 5 IP address classes: Class A, Class B, Class C, Class D and Class E | Does not sort IP addresses into classes |
Address Configuration | Supports manual and DHCP configuration. | Supports manual, DHCP and auto-configuration. Configuration depends on the system requirements. |
Address Configuration | Supports manual and DHCP configuration. | Supports manual, DHCP and auto-configuration. Configuration depends on the system requirements. |
Security Features | No mandatory security measures. Security depends on the application. | Uses Internet Protocol Security (IPsec) for security purposes. |
Encryption & Authentication | No encryption or authentication | Provides encryption and authentication |
Fragmentation | Forwarding routers and senders perform packet fragmentation | Only senders can perform packet fragmentation |
Address Types | Unicast, multicast, broadcast | Unicast, multicast, anycast |
End-to-End Connection Integrity | No end-to-end connection integrity | Supports 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:
- Excellent compatibility: IPv4 has been used since the internet was invented. It’s compatible with virtually all internet and network devices.
- Better availability: IPv4 addresses are readily available, making it easier for users to purchase more addresses, equipment and clients to expand their network.
- Memory efficiency: Devices require less memory cache to store and retrieve IPv4 addresses compared to IPv6 addresses.
Cons:
- Limited address space: IPv4 32-bit addresses provide about 4.3 billion possible combinations, which isn’t sufficient to support the ever-growing number of internet devices.
- Security risks: IPv4 lacks built-in security features and doesn’t support encryption or authentication, so it’s vulnerable to attacks. However, users can add third-party security measures.
- Performance and packet loss issues: Unlike IPv6, IPv4 allows forwarding routers to fragment packets on the path between the source and the destination. This can cause performance issues as the recipients must reassemble the packets.
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:
- Expansive address space: The address pool for IPv6 is approximately 340 undecillion, or 340 trillion trillion trillion. This is more than enough to accommodate all network and internet devices worldwide for the foreseeable future.
- Enhanced security: IPv6 provides built-in network security capabilities, using the Internet Protocol Security (IPsec) protocol to improve data encryption and authorization.
- Improved performance: With IPv6, forwarding routers don’t fragment packets. This eliminates potential performance and data loss issues. Moreover, IPv6 has a simplified header format designed to improve internet connection speed.
Cons:
- Compatibility issues: IPv4 still powers most of the internet, and many devices, systems and infrastructure are based on this older protocol. Many network devices and systems are still incompatible with IPv6, contributing to its slow adoption.
- Complex setup: The transition to IPv6 represents a paradigm shift from what people have always known. The new protocol introduces concepts and features that can be complex and costly.
- Internet traffic filtering issues: IPv6’s new header format requires internet service providers (ISPs) and mobile carriers to adjust internet filtering systems and firewalls.
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.
- Unicast address: This address specifies an identifier for a single protocol interface to which data packets are delivered. It allows one-to-one communication, so a packet sent to a unicast address will be delivered to a single recipient. At the time of writing, most assigned IPv6 addresses are dedicated to the unicast addressing system.
- Multicast address: This address specifies an identifier for a group of interfaces that typically belong to different nodes on the same multicast group. It offers one-to-many communication, where packets sent to a multicast address are delivered to all nodes belonging to the same multicast client.
- Broadcast address: This is a one-to-all communication format in which a broadcast packet or message is sent to all devices on the same network or domain. Remember that IPv6 doesn’t support broadcast addressing.
- Anycast address: This is a one-to-closest communication structure, where a packet sent to an anycast address is delivered to the “nearest” node. In this case, “nearest” isn’t a distance metric; rather, it measures how well the node suits the underlying routing protocol rules. Only IPv6 can perform this method.
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:
- Perfect Privacy: Offers full IPv6 support.
- hide.me VPN: Provides a dual-stack configuration with interoperability capabilities for IPv4 and IPv6 connections.
- AirVPN: Supports both IPv4 and IPv6 traffic.
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
Using IPv6 is better than using IPv4 because IPv6 offers improved security and faster speeds.
Yes. If your router can support both protocols, you should enable IPv4 and IPv6 to get the best of both worlds.
IPv6 is the newest version of the Internet Protocol. You should enable it because it offers better security and speeds compared to IPv4.
In theory, IPv6 is better for gaming, but that depends on whether your favorite games will support it. If the game doesn’t support IPv6, you’re better off using IPv4.