IPv4 vs. IPv6: Which one is better?

IPv4 vs. IPv6—it’s the ultimate showdown in the networking world. If you’ve ever wondered what is IPv4, what is IPv6, and which is better, you’re in the right place. In this article, we’ll compare these two internet protocol versions in depth, covering their key differences, advantages, speed, security aspects, and real-world applications. By the end, you’ll know exactly how IPv4 and IPv6 stack up and why the transition to IPv6 is such a hot topic in the digital world.

What is IPv4?

IPv4 stands for Internet Protocol version 4. Each device connected to the internet gets a unique IPv4 address so that data knows where to go and devices can communicate with each other and with the internet. To understand how IPv4 manages this vast network, let’s look at how these identifiers are structured, their key characteristics, and limitations.

IPv4 address structure

IPv4 assigns a 32-bit number to each device on a network which numbers are grouped into four octets. For example: 192.168.1.10. Each octet ranges from 0 to 255, giving a possible total of around 4.3 billion addresses. Some are public and can route through the internet, while others are private (such as 192.168.x.x) and stay within a home or office network.

IPv4 fits into the TCP/IP model as the main protocol that delivers packets from source to destination. It has been at the core of the internet since the early 1980s. That said, due to the shortage of IPv4 addresses, Network Address Translation (NAT) is commonly used. Beyond its basic structure, IPv4 has several characteristics that have contributed to its long-term use.

Key characteristics of IPv4

1. Widespread support: Virtually every internet-capable device, from old Windows XP machines to new smart TVs, supports IPv4. It’s the common denominator of networking.
2. NAT-reliant: Because IPv4 addresses became scarce, a technology called NAT became common. NAT allows multiple devices on a private network (like your home Wi-Fi) to share a single public IPv4 address. Your router does the translation between your private IP (say 192.168.0.10) and the public IP it presents to the internet.
3. Simple to write and memorize: Dotted-decimal addresses are familiar to many people, such as 192.168.1.1 for a router’s default login page.
4. Broadcast traffic: IPv4 devices can send broadcast messages to all devices on a local network segment using special addresses like 255.255.255.255 or network-specific broadcasts. IPv4 also supports multicast (one-to-many traffic) for things like streaming or IPTV, though usage requires coordination.

While IPv4 has served as the backbone of the internet for decades, its limitations have become increasingly apparent. In particular, the finite number of addresses has led to significant challenges.

Limitations and drawbacks of IPv4

1. IPv4 address exhaustion: The most famous drawback—only ~4.3 billion addresses exist. While that might sound like a lot, we eventually hit a wall. By the 2010s, the free pool of IPv4 addresses was exhausted. In fact, the central pool managed by IANA was depleted in February 2011, and various regional internet registries ran out in the years following. This means no new large blocks of IPv4 addresses could be allocated. The shortage led to increasing use of NAT and even an IPv4 address market where companies buy/sell address blocks.
2. Limited security at the IP layer: IPv4 itself doesn’t include built-in encryption or authentication. Yes, you can secure traffic with protocols like SSL/TLS or VPNs, but IPv4 at the IP layer doesn’t inherently protect the packet contents. Originally, a suite called IPsec was retrofitted into IPv4 to allow encryption/authentication of IP packets, but it’s optional and not universally used. Also, some argue NAT acts as a ‘poor man’s firewall’ (since external hosts can’t directly reach internal IPs). While that’s true to an extent, it’s not a substitute for proper security measures. Relying on NAT for security can be dangerous, and IPv4 networks absolutely still need firewalls and intrusion prevention.
3. Complex NAT setup: Using NAT keeps networks online, but it introduces complexity for peer-to-peer apps and any direct incoming connections. Extra steps (port forwarding) are required to make devices reachable from outside.
4. No built-in auto-configuration: Out of the box, IPv4 needed either manual configuration or a service like DHCP to assign addresses to hosts. There’s no built-in mechanism in IPv4 that says ‘this is your address’ without a DHCP server. IPv6 tackles this with something called SLAAC—Stateless Address Autoconfiguration.

Read more: Are we running out of IP addresses? 5 facts to know

What is IPv6?

IPv6 stands for Internet Protocol version 6—the successor to IPv4. It was developed in the 1990s when it became obvious that we’d eventually run out of IPv4 addresses. IPv6 isn’t just ‘IPv4 with more bits’; it’s a major upgrade that introduces a much larger address space and modernizes many aspects of IP networking.

IPv6 address structure

• Bit-length: 128 bits
• Notation: Eight blocks of four hexadecimal digits separated by colons. For instance: 2001:0db8:0000:0000:0000:0000:0000:0001.
• Abbreviation rules: You can shorten consecutive zeros with :: one time per address (e.g., 2001:db8::1).

IPv6 was designed not just to solve IPv4’s address shortage, but also to simplify and improve IP networking. Here are some important characteristics:

Key characteristics of IPv6

1. Expanded address pool: 128-bit addresses give IPv6 an almost inexhaustible supply of addresses. We’re talking 340 undecillion (that’s 1 followed by 36 zeros) addresses total. To appreciate this: IPv6 allows 4.2 billion times 4.2 billion (i.e., 2^64) addresses per network segment. In practice, this means organizations can get immense blocks of addresses and never worry about NAT or running out.
2. Built-in auto-configuration: IPv6 includes a feature called SLAAC (Stateless Address Autoconfiguration), so devices can set up IP addresses on their own by listening for router announcements. Simply plugging a device into an IPv6 network can be enough for it to get a working IP without any DHCP server.
3. No broadcast: Pv6 got rid of broadcast traffic. In IPv4, broadcast storms and excessive broadcast traffic could be an issue in large networks. IPv6 instead uses targeted multicast for functions like address resolution and network announcements.
4. Simplified packet headers: The IPv6 packet header has been streamlined. It’s a fixed size (40 bytes) with fewer fields than IPv4’s header. Routers process these packets more efficiently than IPv4 packets.

Advantages of IPv6 over IPv4

From the above characteristics, it’s already clear how IPv6 outshines IPv4 in many ways. Let’s summarize the key advantages IPv6 has:

1. Massive address space: Helps avoid IPv4 address exhaustion. No more worrying about running out of IP addresses.
2. Direct addressing: Frees you from NAT for many use cases, so devices can be directly accessible if desired.
3. Better security support: IPv6’s design included IPsec from the start, meaning the protocol expects encryption and authentication of packets to be commonplace. While in practice IPv6 doesn’t automatically encrypt all your traffic—you still need to configure IPsec or use a VPN for that—the support is baked in. Also, without NAT, the security model shifts to using proper firewall policies, which is more transparent and controllable than the accidental ‘security’ of NAT.
4. Less overhead for routers: Without NAT and with simpler headers, routers spend less time processing traffic.
5. Improved mobility: Built-in features make it easier for mobile devices to shift across networks without losing connections.

Now, let’s put IPv4 and IPv6 side by side and compare their key differences across various aspects.

Key differences between IPv4 and IPv6

IPv4 and IPv6 share a core function—moving data across networks—but they differ in address size, performance, and other details. This section covers those differences so you can see how IPv6 addresses many IPv4 issues.

Address space

This one is needs no explanation:

• IPv4: 32-bit, around 4.3 billion possible addresses.
• IPv6: 128-bit, around 340 undecillion addresses.

IPv4 address exhaustion triggered the push for IPv6. With IPv6, you’re unlikely to ever run out of public or private IP addresses.

The problem of IPv4 address exhaustion

IPv4 address exhaustion refers to the moment when regional internet registries ran out of unallocated IPv4 blocks. Many organizations turned to NAT to extend usage or purchased IPv4 addresses from others. This crisis highlighted the need for a replacement protocol. IPv6 completely resolves the exhaustion issue with its vast address pool.

Performance and speed

There’s a common curiosity (and some debates) around IPv4 vs IPv6 speed—which one is faster?

IPv4: IPv4 (20-byte header) has smaller packets by default and no requirement for IPsec, etc., so you might think it’s inherently faster due to less overhead. However, IPv4 often goes through NAT devices which can introduce latency. Also, IPv4 routes might not always be optimal if networks are more congested on IPv4.

IPv6: IPv6 packets are a bit bigger (40-byte header), but the design is streamlined for efficient processing. Importantly, IPv6 avoids NAT, which can reduce delays. In theory, an IPv6 packet might reach its destination with fewer obstacles. Many operating systems and apps also implement a strategy called Happy Eyeballs where they try IPv6 and IPv4 in parallel and use whichever connects first, to avoid any slowdowns if one protocol is lagging.

Security and privacy

IPv6 was built with enhanced security in mind (it originally required IPsec encryption support), but that doesn’t mean IPv4 is completely insecure—nor does it mean IPv6 magically makes everything safe. That said, you won’t be wrong if you’re concerned about staying safe online during and after this transition.

Quick tip: Whether you’re on IPv4 or IPv6, using a quality VPN is one of the easiest ways to bolster your online security. For instance, ExpressVPN offers encrypted tunnels and IP address masking (with IPv6 leak protection), adding an extra layer of privacy on top of your internet connection. It’s a handy tool to have in your arsenal as the internet evolves.

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Device compatibility and adoption

This is a practical difference: how well are devices and systems supporting each protocol?

• IPv4 compatibility: 100% of internet-capable devices support IPv4. It’s a given; without IPv4 you basically couldn’t use the internet in the past. Older hardware and software might only support IPv4.
• IPv6 compatibility: Most modern devices and operating systems now support IPv6, but there are still some that don’t or have it disabled by default.

The good news: If you’re a general user, you typically don’t have to do anything special. Your device will use IPv6 if available, or IPv4 if not. For network administrators, ensuring hardware and software is IPv6-capable has been a checklist item for some time.

Communication types

This difference is a bit technical but important for how network traffic is handled:

IPv4:

• Unicast: One sender to one receiver (the most common type of traffic).
• Broadcast: One sender to all nodes on a network. IPv4 supports broadcast.
• Multicast: One sender to subscribers that are interested. IPv4 supports multicast and it’s used for specific purposes like streaming video to multiple recipients, or routing protocols, etc.
• Anycast: Not an official part of IPv4 standard, but can be implemented: basically assigning the same IP to multiple devices and relying on routing to send a client to the nearest one. IPv4 anycast is used in things like DNS root servers.

IPv6:

• Unicast: Same idea—one-to-one.
• Multicast: Fully supported and even more central to IPv6.
• Broadcast: None. IPv6 does not have a broadcast address. The all-nodes multicast (ff02::1 for link-local scope) is used instead to reach all devices on a LAN. This is a cleaner approach since broadcast can often be abused or cause noise—multicast allows more control.
• Anycast: Officially supported in IPv6. Many IPv6 deployments use anycast for services. For instance, your ISP might give you an anycast DNS resolver IPv6 address—you query it and it goes to whichever server is closest.

Practical effect: The lack of broadcast means less spammy network noise, which can improve performance on busy networks. Using multicast for necessary discovery means only nodes that need to listen will process the packet, others can ignore it. This contributes to routing efficiency and network optimization in IPv6.

Routing efficiency and network optimization

IPv6 design simplifies routing tables. Since IPv6 addresses are allocated in large contiguous blocks, internet backbones can group them without dealing with scattered subnets. Many carriers say this approach helps them scale networks without the overhead of complicated NAT deployments.

How IPv6 improves network security

Let’s zero in on security improvements with IPv6 beyond what we already mentioned:

1. Harder for attackers to do full scans: The huge IPv6 address pool makes random scans less practical.
2. Streamlined end-to-end security: Direct addressing plus IPsec makes encrypted connections easier to manage if admins choose that path.
3. Better multicast handling: The controlled use of multicast avoids the noise of broadcast storms seen in IPv4, which can also reduce potential for local attacks.

It’s worth noting though that IPv6 is not inherently immune to all attacks. Many IPv4 attacks have IPv6 equivalents so you can still get DDoSed on IPv6, you can still have misconfigured devices, etc. But IPv6’s robust design and gigantic address space raise the bar for attackers in some respects and give defenders new tools.

Using ExpressVPN in conjunction with IPv6 is a smart strategy. ExpressVPN will route your traffic through secure servers and mask both your IPv4 and IPv6 addresses. It also prevents any IPv6 leak where your ISP-assigned IPv6 might accidentally be used outside the VPN tunnel. This way, your online activities remain private and secure, taking advantage of IPv6’s benefits without exposing you.

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IPv4 vs IPv6: comparison table

Here are the main differences between IPv4 and IPv6 at a glance:

Next, we’ll discuss which protocol is faster or better for everyday use, and answer the ultimate question: IPv4 vs IPv6—which one should you be using?

Read more: How to configure a static IP address

IPv4 vs. IPv6: Which one is faster and better for users?

Now that you understand the differences, you probably want to know: Should I be using IPv4 or IPv6? Which one will give me faster internet, and which is better overall? Let’s break down the considerations in terms of speed and user experience.

IPv4 vs. IPv6 speed test results

Many tests by internet giants show that IPv6 can deliver slightly faster speeds. In one study, some sites loaded a bit quicker on IPv6—sometimes 10% or more. When a network removes NAT layers, data can travel with fewer stops. On the other hand, the difference can be small in practice. If your ISP’s infrastructure is better optimized for IPv6 or less congested, you may enjoy a speed boost. In other regions, IPv4 might remain just as quick. One concrete way to compare is to conduct your own speed tests or use tools that measure both protocols.

Verdict on speed: On a well-configured network, IPv6 is at least as fast as IPv4, and potentially a bit faster due to reduced NAT overhead and often newer routing infrastructure. You likely won’t see 10x speed just because of IPv6, but a small percentage gain in latency or throughput is possible. More importantly, IPv6 can offer more consistent performance as networks get denser because it alleviates issues like NAT bottlenecks.

How does IPv6 affect internet speed?

For the average user, enabling IPv6 won’t suddenly change your ISP’s bandwidth limits. Your 100 Mbps connection won’t turn into 200 Mbps just by using IPv6. That said, IPv6 can affect the quality of the connection:

• Reduced latency from no NAT: Skipping NAT might reduce small processing delays.
• Cleaner routing paths: Some carriers route IPv6 traffic across newer paths that are less crowded.
• Happy Eyeballs mechanism: Many devices attempt to connect over IPv6 and IPv4 at the same time. Whichever responds first is used. This prevents noticeable slowdowns for the end user.

Is IPv6 better for mobile networks?

Yes. IPv6 is definitely better (and in some cases essential) for mobile networks. Here’s why: mobile carriers faced IPv4 exhaustion early on because every smartphone needs an IP when using data. With billions of phones, carriers didn’t have enough IPv4 to go around without massive NAT and NATting cellular traffic for millions of users is complex and expensive.

By giving each phone an IPv6 address, carriers cut reliance on large-scale NAT systems. This often leads to better performance. For example, T-Mobile in the United States has been heavily using IPv6 for its subscribers. If you’re on a modern mobile network, you probably already have IPv6 support.

Read more: How to change IP address on iPhone

When should you use IPv6 over IPv4?

IPv6 is a sound choice if your devices and ISP support it. You may discover that some applications run smoother without NAT. You may also notice simpler connections for certain online games or direct device-to-device services. The sections below cover special situations that make IPv6 appealing.

Is IPv6 better for business networks?

For many businesses, yes, IPv6 is better or at least increasingly necessary. A business using private IPv4 subnets could struggle if different offices have overlapping addresses, which requires complicated routing. IPv6 provides vast address space so every site can have huge address ranges with no overlap. It simplifies network management. Large cloud providers like AWS also support IPv6 and encourage businesses to adopt it. If your organization expects major growth, IPv6 might reduce future address headaches.

That said, not all businesses have rushed to IPv6. Some have an ‘if it ain’t broke, don’t fix it’ approach, especially if their current IPv4 setup works. But as the IP landscape evolves, there’s a growing incentive for businesses to adopt IPv6 for operational efficiency and to avoid being left behind.

IPv6 and cloud computing

Cloud platforms offer dual-stack support, letting you launch virtual machines or containers with both IPv4 and IPv6. If you serve global clients, running IPv6 on your front-end load balancers ensures that users who rely on IPv6-only connections can reach your apps. Some providers now add extra fees for IPv4 addresses, so moving to IPv6 can reduce costs in certain environments.

Why IPv6 is the standard

IPv4 is still everywhere, but it lacks room to expand. IPv6 was introduced to sustain internet growth. Major websites (Google, Facebook, Netflix, and more) have IPv6 turned on. Many local ISPs supply IPv6 to new customers. Governments have recommended or mandated IPv6 readiness. If you want a protocol that can handle future demands, IPv6 is the standard.

IPv6 adoption in the real world

The global IPv6 adoption rate keeps rising. Some countries have 50% or higher IPv6 usage. Others lag behind. Much of the mobile world uses IPv6. Many home ISPs are moving to dual-stack. If your ISP offers you a modem with IPv6, you can activate it without losing IPv4 access. That means your laptop, phone, and smart TV will all get IPv6 addresses in addition to IPv4.

IPv6 and IoT/5G Networks

The Internet of Things (IoT) includes countless gadgets that each need an IP. With IPv4, only a fraction can get unique addresses. IPv6 allows each connected sensor or device to have its own direct address. That simplifies remote management. In 5G networks, IPv6 is frequently the default because of scale and simpler design. IPv6 makes it easier to assign addresses to cars, smart buildings, and other future-forward technologies.

How to transition from IPv4 to IPv6

Transition can feel complicated, but it typically involves running both protocols together for a while. The next sections break down the most common methods so you can pick the right approach for your home or organization.

Dual-stack technology—the easiest transition method

Dual-stack is the gold standard for transition right now. It means running both IPv4 and IPv6 on the same devices and networks. When you visit a website, your system tries IPv6 first. If it works, great. If not, IPv4 is there to fall back on. This approach avoids sudden breakages and there’s no disruption of older IPv4-based services. Businesses like it because it doesn’t force them to abandon IPv4 networks right away and lets them transition gradually to IPv6.

Tunneling methods for IPv6 on IPv4 networks

What if your ISP doesn’t support IPv6 yet, but you still want to experiment or use it? This is where tunneling comes in. With more native IPv6 around, these tunnels are more of a temporary or niche solution. Ideally, you want native dual-stack. But if that’s not possible, a tunnel can give you IPv6 connectivity. For instance, if you want to learn IPv6 and your ISP doesn’t offer it, setting up a Hurricane Electric tunnel is a good workaround.

Challenges and common issues in IPv6 adoption

Transition isn’t all sunshine and rainbows. People and organizations face challenges like:

1. Legacy hardware: Some older routers do not support IPv6, so you’d need an upgrade.
2. Security config: Network admins who only set IPv4 firewalls might leave IPv6 wide open by accident.
3. User awareness: Many are not aware that IPv6 helps future-proof the internet.
4. Training and cost: Large businesses or ISPs have to train teams and replace older systems, which costs money and time.

One piece of advice if you’re transitioning: enable IPv6 on a small scale and test thoroughly. Maybe start with your lab or a portion of your network. Use dual-stack so you can fall back to IPv4 if something goes wrong. Monitor performance and security.

Let’s wrap up with some frequently asked questions that you may still have about IPv4 vs IPv6.