IPv4 and IPv6. What is the difference?

By Jayden Andrews. November 13, 2019

Every device that connects to the internet – smartphones, computers, servers, routers, or tablets – has a unique Internet Protocol (IP) address that it uses to communicate with other devices. An IP address helps to identify your device and its unique geographical location. As the number of users and devices connecting to the internet increases, so does the need for IP addresses. 

But have you ever wondered how these IP addresses are being generated and distributed to users? And what happens when the world runs out of IP addresses? 

You may not have realized, but the web has undergone a protocol upgrade since 1998 to tackle the shortage of IP addresses. At the moment, there are two IP versions: IPv4 and IPv6. But due to the inefficient use of IPv4, the protocol that a majority of internet services use today, it is no longer capable of supporting the growing number of internet-capable devices. So, the web is slowly transitioning to the more powerful IPv6 address system, which uses a longer 128-bit binary value. 

IPv6 is the next generation IP address standard. It is intended to supplement and eventually replace the old protocol (IPv4). While IPv6 has been around for a while now, it still hasn’t gotten up with its predecessor, IPv4. In short, IPv6 adoption has been slow. 

In this guide, we will not only look at IP address generation and distributions, but we will also take a closer look at IPv4 and IPv6 protocols. So, let’s first find out the main difference between the two protocols. 

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What is IPv4

Internet Protocol version (IPv4) is the fourth version of the IP address system, and it is the primary protocol that a majority of internet services still use today. This protocol is a 32-bit binary value, which can be displayed as four decimal numbers.

It looks like this:

An IPv4 address constitutes a combination of four digits from 0 to 254. So, it can have approximately 4.3 billion unique IP addresses. And out of this number, only 3.7 billion addresses can be assigned. The other 1 billion is set aside for specific uses, such as private addresses space, multicasting, research, and Loopback testing.

The fourth version of the IP address standard was created in 1983 before the internet could spread to all corners of the globe. Surprisingly, it is still the primary protocol that ISPs use to route internet traffic between devices. It doesn’t seem outdated because it has worked pretty well for the past 25 years. But there is one challenge.

Back in 1983, 4.3 billion sounded like a lot. Obviously, no one would have guessed that three decades down the line, people would own internet-capable devices of this magnitude.

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We Have Exhausted IP Addresses

You may have heard that the internet is running out of space. Organizations, such as the African Network Information Center announced that their IPv4 addresses had reached zero in 2017. The American Registry for Internet Numbers had also issued a similar warning in 2015.

But how have we exhausted the 4.3 billion addresses?

First, we have a staggering number of internet-connected devices entering the space each day. Given that most phones today are internet-capable, this means they require their own IP addresses. But to some people, 4.3 billion still seems like a stretch.

Here is the thing. As mentioned earlier, inefficiency is one of the main reasons we have exhausted the IPv4 addresses. Back in the 1980s, large corporations were allocated millions of IP addresses, far more than they needed. Because of this, there are millions or even billions of owned-but-unused IP addresses out there. Such wastages have contributed significantly to the exhaustion of the 32-bit IP addresses.

There is nothing to worry about, though. The internet is not shutting down anytime soon. In fact, the team that designed IPv6 had predicted the exhaustion of IPv4. But now that it has happened, IPv6 should be rolled out faster.

What is IPv6

The sixth version of the internet protocol (IPv6) got finalized in 1998 and was later established as an Internet Standard in 2017. It is the enhanced version of the IPv4 protocol, except that there are a lot more IP addresses available.

Besides this, there are significant differences between these two protocol versions, including the number of addresses and their features. Here is how an IPv6 address looks like:


IPv6 appears as eight groups of four hexadecimal digits. Unlike IPv4, colons separate each of these groups. IPv6 contains 128 bits, so instead of using zero through 10 (base 10) only, it can use an additional f (base 16). Basically, this gives us a total combination of 3.4X10^28 (340 undecillion) addresses, meaning that we won’t worry about running out of IPv6 addresses anytime soon.

The staggeringly high number of IP addresses means that each device will have its own unique address. As we speak, only routers have unique addresses. The individual devices that connect to these routers are usually assigned non-unique addresses.

Why Switching to IPv6 Has Been Slow?

While IPv6 is the newest standard that can support more devices on the internet, many service providers are still reluctant to switch to this technology due to various reasons. Data centers and end-users have also contributed to the slow transition process.

Here are the main reasons why most stakeholders are slow to transition to IPv6:

1. IPv6 Does Not Support Backward Compatibility with IPv4

If your device and ISP use the IPv6 protocol, but a website you are trying to visit run on IPv4, you won’t be able to access it. The only way you can get through this block is when your device is compatible with both protocols.

While most networking devices on the market today support IPv6, it is still hard to make a seamless worldwide transition. All ISPs, operating systems, and equipment need to upgrade to the new technology. The only way ISPs can manage this transition is to run both protocols, which can be costly. Actually, one of the most prominent factors that are holding back IPv6 adoption is cost. It is expensive and time-consuming to upgrade all routers, switches, and servers that have long relied solely on IPv4.

2. The Benefits to the End-User Are Not Apparent

IP addresses are managed by five regional registries – one for each continent. So far, these organizations have exhausted their IPv4 addresses. While that is the case, some companies still find it hard to spend their money on new technology, if their clients wouldn’t see the value in it. True, the creation of more IP addresses is an important business task for providers, but the end-user may not see its immediate benefit.

So, to manage the mess, a majority of ISPs usually assign dynamic IP addresses to users. What it means is that your IP address is likely to change each time you connect to the internet, especially when you are connecting through a different network. So, devices that are not connected at any time will relinquish their IP addresses to be used by other internet users.

While this strategy has helped to slow down the depletion of IPv4 addresses, it has also contributed to the slow adoption of IPv6. We can’t deny the transition is happening, but currently, the two IP standards operate simultaneously, until we transition fully to IPv6.

With that said, IPv6 is steadily gaining popularity. Most ISPs are already rolling out IPv6 capabilities. The only problem is that the rollout is carried out at different rates around the world, mostly in developed countries.

IPv4 vs. IPv6: What is the difference?

By now, we all know that IPv6 help to fix the problem of limited IP addresses, but it doesn’t stop there. It also offers other benefits that IPv4 lacks. Here are some of them:

  • Better Security: Designers of IPv6 incorporated various security measures. It guarantees confidentiality, data integrity, and authentication more than IPv4. IPv6 Internet Control Message Protocol (ICMP) packets often use IPSec, which is much safer. ICMP is susceptible to malware attacks, so most corporate firewalls often block it.
  • Auto-Configuration: One of the main differences between the two protocol versions is the way they allocate IP addresses. Most people love IPv6 because it allows devices to assign themselves IP addresses automatically. Typically, devices have to connect to a server first to get an IP address assigned to them. With IPv6, devices can generate their unique IP addresses using their MAC address, which is unique to every internet-compatible device.
  • No Geographical Limitations: From the onset, IPv4 was designed to favor the US. In fact, 50% of IPv4 addresses were reserved for users in this country. IPv6, on the other hand, is available for everyone in the world.
  • Better Connectivity: With IPv6, all devices can have their own IP addresses. So, each device can communicate directly with a website. There is no need for Network Address Translation (NAT).
  • Seamless Rerouting: Unlike IPv4, the new protocol has consistent headers, meaning that the code for routing IPv6 addresses is much simpler and involves minimal hardware processing. For this reason, IPv6 tends to offer a better user experience.

As you can see, IPv6 has more benefits than its predecessor. However, when it comes to speed, IPv4 is slightly faster than IPv6. But the difference can only be a fraction of a second.

So, if your ISP offers IPv6 and you have a device and router that support it, you should turn it on. But before you even thought of activating it, you should first check if you are already using it. IPv6 testing sites like www.test-ipv6.com will simplify the process for you.

With your IPv6 enabled, you can access IPv6 sites natively or using a transition mechanism. The most common transition mechanism is 6to4. But if your router allows for native IPv6 connection, consider using this option because you will skip the transition process.

IPv6 and VPNs

A significant percentage of VPN providers operate solely on IPv4. What this means is that if you submit a request for a site that runs on IPv6, it will act on it using an IPv6 DNS server outside the VPN framework. Your traffic will exit the secure VPN network and goes through your ISP, thus making you susceptible to IPv6 leaks. It also means that your ISP can monitor your online behavior, which beats the purpose of using a VPN in the first place.

To avoid such risks, you should always use a VPN service that supports IPv6. Luckily, some providers have upgraded their systems to support IPv6 traffic. If you are not sure how your VPN provider manages IPv6 traffic, it is better to test your connection for IPv6 leaks.

Stay Safe with IPv6

At the moment, IPv4 still surpasses IPv6, but the new IP standard will fully replace IPv4 at some point. While there isn’t much you can do, as a consumer, to prepare for IPv6, you should at least be careful when selecting service providers.

Also, if your device is slightly old, there are high chances that it is not IPv6 compatible. And if your device supports the new technology, you can activate IPv6 on your internet connection settings. Fortunately, a majority of modern models come with this setting enabled by default.

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