IPv4 vs. IPv6: Why the Internet Needed a New Address System

Introduction

To connect to the Internet, all devices need their own unique identifier. This identifier is called the IP address (Internet Protocol address). Without one, the data wouldn’t have a destination, would have nowhere to go. It would be like sending a snail mail without the receiver's address written on it.  

So far, the Internet has been working on IPv4 (Internet Protocol version 4), from the initial email systems to the cloud services and large platforms we use today. But IPv4 has a limit: it can only provide about 4.3 billion addresses. That was sufficient in the 1980s, but nowadays, with more than 5 billion Internet users and tens of billions of devices now online, IPv4 simply can’t absorb the demand.

Here's why IPv6 (Internet Protocol version 6) was created. IPv6 was developed to fix the address shortage and ensure the Internet can continue expanding. In this article, we’ll see the IPv4 vs. IPv6 debate, explain why the change matters, explain their differences, and guide you on how to get your network ready for IPv6.

What Is an IP Address?

An IP address is a digital tag given to all devices within a network. It’s an unrepeatable combination of numbers (or numbers and letters in the case of IPv6). It permits data packets (which we could say are the “letters” of the Internet, continuing with our analogy of postal addresses and IPs) to go from the sender to the receiver successfully.

To clarify this further, when you visit any website, your device (laptop, smartphone, tablet, etc.) sends a request to the server’s IP address. Then, the server replies by sending the website’s data back to your device’s IP.

Without IP addresses, the Internet would be a mess of data lost, navigating in the cyberspace without a clear destination. Data would not know where to go.  

We have two main kinds of IPs:

Public IPs: These are worldwide unique, accessible from the internet and are assigned by your Internet Service Provider (ISP), typically to your router.

Private IPs: Private IPs are used internal (for example, within your home or office). All the devices share one public IP via NAT (Network Address Translation).

Expert Tip: Knowing if your device uses IPv4 or IPv6 can make troubleshooting slow connections or compatibility issues easy.

Understanding IPv4: Structure, Limits, and Address Types

IPv4: Structure

IPv4 is a 32-bit addressing system written in four sets of numbers separated by dots (e.g., 192.168.1.1). Each group can range from 0 to 255. This structure can accommodate approximately 4.3 billion unique addresses.

IPv4 was created in 1981. At that time, it was beyond anyone’s imagination that a couple of decades later, there would be billions of people and their devices online at the same time. IPv4 could cover the Internet's needs at the moment of its creation, but not those of 2025.

Availability and IPv4 Exhaustion

As the Internet kept expanding, the number of available IPv4 addresses began to run out. By 2019, all main regional Internet registries, including APNIC, had already allocated their last blocks of IPv4 addresses. That’s what’s called IPv4 exhaustion.

To expand the life of IPv4, engineers developed NAT (Network Address Translation). With NAT, it became possible for several devices in a home or office to share the same public IP. To exemplify it, your ISP (Internet Service Provider) gives your router one public IPv4 address, while NAT assigns private addresses to each device connected to it.

While NAT works, it just circumvents the problem without eliminating it. It’s a temporary fix. With the burst of IoT devices, smart refrigerators to sensors or software, IPv4 plainly cannot cover the entire global demand.

Expert Tip: If you run a server or use VoIP, NAT can bring connectivity problems. If that’s your case, turn to IPv6 as it eradicates those issues, giving every device a public address.

Public vs. Private IPv4 Addresses

• Public IPv4: Unique, Internet-routable addresses that make your network globally recognizable.
• Private IPv4: Used for internal networks (e.g., 192.168.x.x, 10.x.x.x). These cannot be accessed directly from the Internet.

Understanding IPv6: The Next Generation of Internet Addressing

In the discussion IPv4 vs. IPv6, IPv6 emerges as the solution that solves the address outage. Let’s see its specs and capabilities.

IPv6: structure

IPv6 is a 128-bit addressing system. It is written in the hexadecimal system (a mix of numbers and letters). A typical IPv6 address looks like this:
2001:0db8:85a3:0000:0000:8a2e:0370:7334.

Due to its size, IPv6 can create about 340 undecillion unique addresses (that’s 340 followed by 36 zeros). In brief, IPv6 can assign a unique IP to every device on Earth and still have plenty of capability left.

Advantages of IPv6

• Literally limitless addresses: Eradicates the shortage crisis.
• No need for NAT: Every device can have a unique, universally reachable address.
• Built-in security: IPv6 mandates IPSec (Internet Protocol Security), which  authenticates and encrypts traffic.
• Simplified routing: Organizes how routers forward traffic, improving efficiency.
• Automatic configuration: Devices can assign themselves an IPv6 address when they join a network. This cuts the need for manual setup.

Stat: According to Google IPv6 Stats, from barely 1% in 2012, now Google runs over 45% its traffic over IPv6.

Public vs. Private IP Addresses in IPv6

IPv6 also endorses the concepts of public and private (local) addresses.

• Public IPv6: Globally unique, routable on the Internet.
• Unique Local Address (ULA): Comparable to private IPv4, used within a home or corporate network.
• Link-local Addresses: These are automatically assigned to each interface for communication within the same local link (starting with fe80::).

Thanks to this flexibility, networks can run securely internally while still benefiting from the colossal address pool of IPv6.

Why IPv6 Matters for the Future of Networking

IPv6 enables the growth of the Internet of Things (IoT), supports modern applications like video conferencing, cloud computing, and streaming, and decreases dependence on temporary fixes like NAT.

Governments and ISPs around the globe are encouraging  IPv6 adoption. For example:

• The U.S. government has mandated IPv6 adoption across federal agencies.
• Major ISPs in Europe and Asia already provide IPv6 by default.

Expert Tip: If you’re upgrading your network equipment, always opt for routers and switches that come with the “IPv6-ready” label.

IPv6 adoption empowers the next upsurge of innovation:

• Internet of Things (IoT): Billions of sensors and smart devices need unique IPs.
• Cloud and Edge Computing: Direct device-to-server connections improve performance.
• 5G Networks: Mobile carriers rely on IPv6 for competent device management.
• Zero Trust Security: Built-in IPsec supports end-to-end encryption.

IPv4 vs. IPv6: Transition Challenges

Although IPv6 solves the long-term problem of address exhaustion, the change from IPv4 to IPv6 hasn’t been flawless. The two protocols are not backwards compatible. This means that an IPv6-only device cannot directly communicate with an IPv4-only server. This incompatibility has shaped an intricate, complex transition phase that necessitates cautious coordination across networks, ISPs, and software developers.

To bridge the gap, today’s Internet often relies on a dual-stack model, where both IPv4 and IPv6 run side by side. This setup keeps networks functioning during the transition, but it also brings its own challenges.

Key Obstacles That Slow IPv6 Adoption

• Dual-Stack Overhead: Running two protocols at once forces routers, firewalls, and servers to manage separate address spaces. This augments memory usage and processing demands.
• Older Hardware: Many older routers, modems, and business systems don’t support IPv6. Some need their firmware to be updated, but many times those updates are no longer available.
• Irregular ISP Readiness: Some Internet service providers in countries like India, Germany, and France lead in the introduction of IPv6, while many smaller or rural ISPs still depend completely on IPv4.
• Apps Compatibility: Older applications, security tools, and enterprise software originally designed for IPv4 may fail or perform unpredictably when IPv6 is active.
• Network Management Complications: IT teams must deal with two address systems simultaneously, solve hybrid connectivity issues, and sustain consistent security policies across both IPv4 and IPv6 systems.
• Little Motivation for the Users: For many domestic users or small businesses, IPv6 doesn’t offer obvious improvements. For that reason, such users tend to think that upgrading to IPv6 is an option, not a necessity.

All the challenges are not preventing us from moving forward.  Currently, dual-stack networking remains the preferred solution for keeping everything working properly. An increasing number of networks are adopting this dual-stack system on a daily basis.  

Expert Tip: If you manage a network, first test IPv6 in a small, controlled environment. Look for DNS resolution errors, firewall conflicts, or application performance before deploying it across all your infrastructure.

IPv4 vs. IPv6: Main Differences

Expert Tip: If you turn on IPv6 now, you’ll be configuring your network to be compatible with the future, especially for the rise of new apps, cloud services, and smart devices.

How to Check if Your Network Supports IPv6

To verify if your devices are ready to adopt IPv6, here’s a simple step-by-step guide:

1. Check Your Device

• Windows: Go to Settings > Network & Internet > Properties and look for “IPv6 connectivity.”
• macOS: Open System Preferences > Network > Advanced > TCP/IP. If an IPv6 address appears, you’re connected.
• Linux: Open a terminal and type ifconfig or ip a. See if there are any entries beginning with inet6.

2. Use Free Online Tools

• Visit Test-IPv6.com. The site runs a quick test and confirms whether IPv6 is active.

3. Verify Your Router

• Log into your router (frequently at 192.168.1.1).
• Go to WAN or Internet Settings and confirm that IPv6 is enabled.

4. Run a Ping Test

• Open the Command Prompt (in Windows) or Terminal (in Mac or Linux).
• Type: ping -6 google.com.
• A successful reply means IPv6 is functioning.

5. Enable IPv6

• If your router or OS has IPv6 turned off, switch it to Enabled or DHCPv6.
• Save, restart, and test again.

Expert Tip: If your ISP doesn’t support IPv6 yet, you can still turn it on within your local network. This is a simple step to prepare you for your future networking needs.

Frequently Asked Questions (FAQ)

1. Can IPv4 and IPv6 work together?
Yes. Most networks use a dual-stack configuration that copes with both protocols at the same time. This is the most used setup during the transition.

2. Do I need new hardware to use IPv6?
Most modern devices (such as routers or modems) and operating systems already support IPv6. Older equipment may need firmware updates or, in some cases, be replaced.

3. Is IPv6 faster than IPv4?
Not necessarily. Internet speed depends mainly on your Internet service provider and overall setup. Nevertheless, IPv6 can cut latency and make connections more direct by eliminating NAT, which tends to improve reliability.

4. What can I do if my Internet provider still doesn’t support IPv6?
You’ll continue using IPv4 until it does. Some service providers also offer IPv6 tunneling, which lets you access IPv6 networks over an IPv4 connection.

5. Will IPv4 eventually disappear completely?
Not soon. IPv4 will still coexist with IPv6 for years. Yet, IPv6 adoption will continue to expand until it becomes the default standard.

Conclusion: The Debate IPv4 vs IPv6 Is a Matter of Evolution

The discussion of IPv4 vs. IPv6 isn’t about which is “better”; it’s about evolution and survival. IPv4 powered the Internet for over 40 years, but it is now exhausted. IPv6 provides the scale, security, and performance needed for the future of connectivity.

• For beginners, IPv6 means faster and more reliable Internet without worrying about running out of addresses.
• For technicians, it offers better performance, security, and scalability.
• For DIYers, enabling IPv6 now prepares your smart home and overall Internet usage for future additions or upgrades.

The transition is already on its way, with Google, Cloudflare, and major ISPs leading the change.

If you haven’t already done it, check if your devices and network are IPv6-ready:

• Check your devices
• Enable IPv6 on your router
• Go for IPv6-ready hardware

The Internet isn’t going back, so move forward with it.