PlayInfoBox

Home /Network /IPv4 vs IPv6: What's the Difference and Why It Matters

IPv4 vs IPv6: What's the Difference and Why It Matters

Every device on the internet needs an address, and the internet is in the middle of a decades-long, mostly invisible transition between two different addressing systems.

IPv4 uses 32-bit addresses written as four numbers

A typical IPv4 address looks like 192.168.1.1 β€” four numbers separated by dots, each representing part of a 32-bit binary address, which provides roughly 4.3 billion possible unique addresses.

IPv6 uses much longer 128-bit addresses

IPv6 addresses are written as eight groups of hexadecimal digits separated by colons (for example, 2001:0db8::1). Because it uses 128 bits instead of 32, the total address space is vastly larger than IPv4's.

The global pool of new IPv4 addresses ran out years ago

IANA, the body that allocates address blocks to regional registries, exhausted its free pool of new IPv4 addresses in 2011. Regional registries around the world subsequently ran through their own remaining allocations at different points afterward.

IPv6 exists to solve the address shortage at the root

IPv6 was designed specifically to provide a functionally inexhaustible supply of unique addresses, anticipating that the explosive growth of internet-connected devices would eventually outpace what IPv4's address space could support.

NAT extended IPv4's usable life for years

Network Address Translation (NAT) lets many devices on a home or office network share a single public IPv4 address, which significantly delayed full IPv4 exhaustion by reducing how many public addresses were actually needed.

Most modern networks run both protocols at once

"Dual stack" setups, where a device and network support IPv4 and IPv6 simultaneously, are the most common way the transition has actually played out, letting older IPv4-only services keep working while IPv6 usage grows alongside it.

IPv4 and IPv6 do not talk to each other natively

The two protocols are not directly interoperable at the protocol level, so connecting an IPv4-only device to an IPv6-only one requires a translation mechanism or a dual-stack intermediary rather than happening automatically.

Most people never notice which one they are using

Home routers, mobile carriers, and operating systems generally handle the choice between IPv4 and IPv6 automatically in the background, which is why the vast majority of internet users have never had to think about the difference at all.

How to read and shorten an IPv6 address

An IPv6 address has eight groups of four hexadecimal digits. To shorten it, you may drop leading zeros in each group, and you may replace one run of consecutive all-zero groups with a double colon, but only once per address. So 2001:0db8:0000:0000:0000:0000:0000:0001 becomes 2001:db8::1. The prefix 2001:db8::/32 is reserved for documentation, which is why it appears in so many examples.

Exhaustion happened at different times in different regions

After IANA handed out its last blocks in early 2011, each regional registry reached its own point of running low. The Asia-Pacific registry reached its final-block policy in April 2011, the European registry did so in 2012, the Latin American registry in 2014, and the North American registry declared its free pool depleted in September 2015. Definitions of exhaustion differ slightly between registries, and some still allocate small amounts under special policies or from recovered space. Networks that need more IPv4 addresses today usually obtain them by transfer or lease from others.

IPv6 is designed to work without NAT

Because there are enough addresses for every device to have its own globally unique one, IPv6 does not need NAT to conserve space. That restores direct end-to-end connectivity, which helps applications such as voice calls, games and file sharing. It does not mean devices are unprotected: a home router normally includes a stateful firewall that blocks unsolicited incoming connections by default, and NAT was never meant to be a security feature in the first place.

The tools that connect the two worlds

Besides dual stack, networks use translation and tunneling. NAT64 with DNS64 lets IPv6-only clients reach IPv4-only servers, a design common on mobile networks. Tunnels carry IPv6 packets inside IPv4 across parts of a network that have not been upgraded. Some mobile and home providers use a combination called 464XLAT to keep older IPv4-only apps working on IPv6-only access networks. Users generally see none of this, but it explains why a network can be IPv6-only and still reach nearly every website.

How widely is IPv6 used today

Adoption is measured by services such as Google's statistics, which count the share of users who reach Google over IPv6. According to an Internet Society analysis, that share came close to 50 percent in mid-2025. The spread between countries is large: some countries have well over 60 percent while others are in the low single digits or the teens. These numbers move over time, so check a current source if you need an up-to-date figure.

A shortage nobody saw coming this soon

When IPv4 was designed decades ago, roughly 4.3 billion addresses seemed effectively limitless. The explosive growth of the internet, and later of smartphones and connected devices, made that number a real constraint far sooner than originally assumed, which is what set the transition to IPv6 in motion.

Why the transition has taken so long

Because IPv4 and IPv6 are not natively interoperable, upgrading the entire internet requires network operators, device makers, and service providers to support both protocols simultaneously for a long overlap period, rather than being able to switch over all at once. That coordination problem, not any lack of technical readiness, is the main reason the shift has stretched across decades.

What it actually means for an everyday user

For nearly all everyday browsing and app use, the underlying protocol is invisible β€” your device, router, and internet provider negotiate whichever protocol is available automatically. The distinction mainly matters to network engineers, ISPs, and anyone directly configuring server or router settings.

Does IPv6 make the internet faster or more secure?

Not automatically. IPv6 has a simpler fixed header and removes some processing from routers, but real-world speed depends mainly on the network path, the servers and the congestion on the way. In some cases, IPv6 paths are faster, in others slower, and a well-configured dual-stack connection normally picks whichever works best. IPsec support was designed into the original IPv6 specification, but that does not make an ordinary connection safe by itself; firewalls, updates and encryption at the application level still matter.

When the difference does matter to you

You may notice IPv6 when you run a home server, a game host or a security camera that you reach from outside, because the address, firewall rules and DNS records are different from an IPv4 setup. Businesses with older devices that only understand IPv4 also need a plan. If a website works on one network but not another, or some devices cannot connect on a mobile hotspot, a misconfigured IPv6 setting is one of the possible causes, and temporarily testing with IPv6 turned off is a standard diagnostic step.

Frequently Asked Questions

Do I need to do anything to start using IPv6?

Usually no. Most modern routers, operating systems, and internet providers handle the choice between IPv4 and IPv6 automatically without any action needed from the average user.

Why hasn't IPv6 fully replaced IPv4 yet?

The two protocols are not natively compatible, so replacing IPv4 requires broad, coordinated support for IPv6 across networks, devices, and services during a long transition period, rather than a single global switch-over.

Can an IPv4 device communicate directly with an IPv6-only device?

Not natively β€” the two protocols require a translation mechanism or a dual-stack device that supports both in order to bridge the gap.

How can I tell which protocol my connection is using?

Your device's network settings typically show both an IPv4 and, if supported, an IPv6 address at the same time, since most connections today run in dual-stack mode using both simultaneously.

Is it safe to disable IPv6 on my computer?

It usually works, but it is not generally recommended as a fix, because some systems and applications assume IPv6 is present, and turning it off can cause odd side effects. If you suspect a problem, test with it off, then fix the underlying configuration rather than leaving it disabled.

Why do IPv6 addresses look so long?

Because they are four times as long in bits as IPv4 addresses: 128 bits instead of 32. They are written in hexadecimal and can be shortened, but they are not designed to be memorized; names from DNS are used for people.