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IPv4 vs. IPv6: A Comparison on These Two Protocols

The majority of Internet users know that an IP address is a unique string of numbers that is used to identify a device when communicating over a network. It’s one of the essential things that make the Internet work. Without it, Internet users will lose all network traffic—they won’t be able to get to their intended destination site, and even if they did make it, the site wouldn’t know how to send the response back to the sender.

It’s like sending ‘snail mail’ without the recipient’s and sender’s addresses. Or riding a taxi and not telling the driver the exact address of your destination. You get the picture.

IP addresses are very important, and you should be aware that the world is running out of IP addresses.

Don’t panic just yet. IPv4 address exhaustion has been predicted since the 1980s, and the top-level address blocks have been used up as early as 2011. Naturally, the organizations that manage the IP address space had addressed this problem as early as 1998 by coming up with a new protocol: the IPv6.

IPv4: The past and the present

Version four of the Internet Protocol is as old as the Internet, or at least the early “network of networks” version of it. While the World Wide Web came into form in 1990, IPv4 was already in the works since 1983—and it’s still being used until now. Watch the video below to understand IPv4 better:

At its core, an IPv4 address uses 32 binary bits made up of four octets, with each octet separated by dots. A sample IPv4 address will look like this: Since it is only 32-bit, the IPv4 space contains a little less than 4.3 billion IP addresses only. You can easily see why it’s running out—there are currently around 3.2 billion Internet users, and most of these users (including you and me) have more than two devices connected to the Internet.

Although there’s the Network Address Translation (NAT) which was primarily developed to conserve IP addresses, depletion is still occurring mainly due to the following:

  • Assigned but unused IP addresses: There are millions of IPv4 addresses that have been assigned to organizations, but these were unused. Some of these companies gave back or sold these IP addresses, but IPv4 is still being depleted because of the next item on the list.
  • Every device has its own IP address: If each Internet user has two devices, that will be 6.4 billion IP addresses—way less than the available IPv4 addresses. NAT has helped delay IPv4 exhaustion by allowing a single IP address on a device (the router) to represent a group of computers that connect to the Internet.

However, as the world population continues to grow, the number of households will also grow, and with it, the number of networks that need public IPv4 addresses. Time has come when NAT finally can’t do anything about this anymore.

There seems to be no other way to go about it—IPv4 will become used up. The only logical solution then is to replace it with another protocol, which is why IPv6 is here.

IPv6: The present and the future

IPv6 uses 128 binary bits and provides the world with virtually unlimited number of IP addresses—roughly around 340,282,366,920,938,463,463,374,607,431,768,211,456. That’s enough IP addresses to last a lifetime, so we’re safe. To learn more about IPv6, watch this video:

Basically, IPv6 makes use of 32 hexadecimal numbers divided into eight quartets, with each quartet divided by a colon. It looks something like this: 2001:0db6:46a3:0000:0000:8a2e:0370:8223. Aside from the length, structure, and the fact that it can last forever, IPv6 is different from IPv4 because of these advantages:

  • It can do away with NAT: With IPv6, there’s no more need for NAT as every device can have its own IP address.
  • It has better peer to peer networking: Because NAT won’t stand in the way, peer to peer communications will become possible with IPv6. Each device can have its own IP address, so file sharing is made easy. People no longer have to rely on cloud storage.
  • It simplifies data packet headers: The IP header is simplified and more flexible as some of the fields present in IPv4 can be removed or moved to an extension header. These fields are header length, flags, identification, fragment offset, and header checksum.
  • It is deemed more secure: IPv6 supports IPsec (Internet Protocol Security). Each packet is encrypted and anti-spoof, making it difficult for hackers to intercept. Of course, the protocol has vulnerabilities—Man-in-the-Middle (MITM) attacks are still possible using a different strategy.

For sure, a lot more issues and security threats will pop up when IPv6 becomes widely used. For instance, companies are already concerned with the fact that NAT won’t be used with IPv6. However, NAT can be easily replaced by a stronger firewall with stateful inspection packets.

IPv6: Where are we at?

We are still in the early stages of IPv6 usage, and only a few have made a transition to this protocol. Based on Google’s monitoring, only less than 25% of Internet traffic is from IPv6 as of December 2018.


The main reason why IPv6 is not globally implemented yet is that it’s expensive. Although it’s version six of the Internet Protocol, it isn’t backward compatible with IPv4. So it’s like a whole new protocol, not just an upgraded one. This means that there’s a need for new server software and equipment since we can’t use the ones for IPv4.

Nevertheless, router manufacturers have started to deliver IPv6-compatible routers. Large ISPs have also rolled out IPv6 capabilities to users while operating systems (like the latest versions of Windows) already have IPv6 support.

As a matter of fact, you might already be using IPv6 now. This sounds great unless you’re using a VPN (more on this later), but you can do the following tests to check if IPv6 is enabled:

IPv6 network test1

IPv6 website test

For websites, this shift from IPv4 to IPv6 means that owners need two versions of their sites—one for IPv4 traffic and the other for IPv6. Alternatively, a translator service can also be used. But in both solutions, website owners are in for a tedious and expensive transition.

Should you be using IPv6?

It’s inevitable. Time will come when everyone is forced to use IPv6. This is ultimately a good thing because when you compare IPv4 vs. IPv6, IPv6 has more functionality and it gives the whole world a lot more IP addresses. For now, however, IPv4 is still widely used.

So as an Internet user, should you make the shift now? If you are using a VPN, the answer is a big no. It’s best not to use IPv6 yet because most VPN providers still don’t have IPv6 capability yet. For example, our top VPN provider which is IPVanish currently only supports IPv4 traffic and is still getting ready for IPv6.

IPVanish statement ipv6

On the other hand, CyberGhost, which is also among the best VPN providers we’ve tried, already supports IPv6 traffic. It’s one of the few providers that support the new protocol as even one of the most popular VPN providers, ExpressVPN, still don’t support IPv6.

What happens when you are using IPv6 with a non-compatible VPN? IPv6 traffic will run out of the VPN tunnel, causing an IP leak. This happens because your IPv6 traffic will be routed through your ISP instead of your VPN. This traffic won’t be encrypted, so your ISP can see all your activities. In addition, anyone can see your IPv6 address and trace it back to you.

This defeats the purpose of your VPN. Some providers, such as PureVPN, has a feature that protects users from IPv6 leaks.

Aside from this feature, you might also want to turn off IPv6 in your computer. The next section will teach you how.

How to turn off IPv6

To avoid the scenario in the previous section, start by checking if your network or ISP supports IPv6. As mentioned previously, you may use https://test-ipv6.com/ or https://ip6.nl/ to check this. The image below is from the latter:

IPv6 network are you connected

If the test shows that there’s no IPv6 vulnerability, then you’re safe. However, when it shows otherwise, you need to turn it off in your operating system. For Windows users, follow these steps:

  1. Go to Settings > Network & Internet > Network & Sharing Center.

Windows settings ipv6

  1. Click on Change adapter options.

Windows settings ipv6 step 2

  1. Right-click on your main Internet connection, and select Properties.

Windows ipv6 settings Step 3

  1. Look for Internet Protocol Version 6 (TCP/IPv6) on the list and uncheck the box.

Windows ipv6 Step 4

  1. Click OK.

To turn off IPv6 on Mac, do these:

  1. Go to System Preferences > Network.
  2. Click on Advanced > TCP/IP tab.
  3. Change the Configure IPv6 dropdown to Off.

Just like what IPVanish said, when IPv6 becomes globally implemented, VPN providers will surely follow suit and update their servers and software. For now, the best thing to do is to disable IPv6 connection to avoid the current vulnerability.

IPv4 vs. IPv6: What a VPN user should choose

The tweeted photo below summarizes the basic differences between IPv4 and IPv6:


The world will definitely go towards IPv6 in the future, so there’s not much choice. As to when exactly, only time can tell. For now, you need to use the protocol that is still widely used, especially if you are a VPN user—and that’s IPv4.

Even the best VPN providers are still gearing towards IPv6 but aren’t there yet. To avoid IPv6 leaks, take advantage of VPN features and disable IPv6 in your computer. While we’re at it, make sure that you test your VPN regularly. You can check out this guide on how to do a thorough VPN test.

When VPN providers finally update their system so that it works with IPv6, you can turn your IPv6 back on and enjoy its functionalities.

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