The IPv4 Address Exhaustion Problem
IPv4 uses 32-bit addresses, providing 2^32 — approximately 4.3 billion — unique addresses. When the internet was designed in the 1970s and 1980s, this seemed more than sufficient. The designers could not have anticipated that billions of humans would each own multiple internet-connected devices.
IANA (the Internet Assigned Numbers Authority) exhausted its free pool of IPv4 addresses in February 2011. Regional Internet Registries (RIRs) that allocate addresses to ISPs and organizations ran out in succession: APNIC (Asia-Pacific) in April 2011, RIPE NCC (Europe) in September 2012, LACNIC (Latin America) in June 2014, ARIN (North America) in September 2015, and AFRINIC (Africa) in 2019.
The internet did not collapse because of two stopgap measures: NAT (Network Address Translation) allows many devices to share a single public IP address through a router, and address trading markets allow organizations to buy and sell IPv4 blocks. But these are workarounds, not solutions — NAT breaks end-to-end connectivity, complicates applications, and adds latency.
Check whether your device has been assigned an IPv4 or IPv6 address using our IP lookup tool — many ISPs now assign IPv6 by default while keeping IPv4 for legacy compatibility.
IPv6: The Solution
IPv6 uses 128-bit addresses, providing 2^128 — approximately 340 undecillion (3.4 × 10^38) — unique addresses. This is an almost incomprehensibly large number: roughly 670 quadrillion addresses for every square millimeter of Earth's surface. IPv6 was designed with the assumption that every device on earth — including IoT sensors, appliances, and infrastructure — could have a globally unique address.
IPv6 addresses look different from IPv4. Where IPv4 uses four decimal octets (203.0.113.42), IPv6 uses eight groups of four hexadecimal digits separated by colons: 2001:0db8:85a3:0000:0000:8a2e:0370:7334. Leading zeros in each group can be omitted, and one consecutive run of all-zero groups can be replaced with ::, giving the shortened form: 2001:db8:85a3::8a2e:370:7334.
Beyond address space, IPv6 includes technical improvements:
- Simplified header: The IPv6 header has fewer fields than IPv4, enabling faster router processing.
- No NAT required: Every device gets a globally routable address, restoring end-to-end connectivity.
- Stateless Address Autoconfiguration (SLAAC): Devices can configure their own IPv6 address from network prefixes without a DHCP server.
- Mandatory IPsec support: Built-in cryptographic security at the network layer.
- Improved multicast: Broadcast is eliminated in favor of more efficient multicast and anycast.
IPv6 Transition Mechanisms
The internet cannot switch from IPv4 to IPv6 overnight — there are billions of devices and legacy systems. Transition mechanisms allow IPv4 and IPv6 to coexist during the migration period:
Dual Stack: The most common approach. Devices and networks run both IPv4 and IPv6 simultaneously. A website with both an A record (IPv4) and AAAA record (IPv6) can serve both. Browsers prefer IPv6 when available (using the "Happy Eyeballs" algorithm — RFC 8305 — which races IPv6 and IPv4 connections and uses whichever responds first).
6to4 and Teredo: Tunneling mechanisms that encapsulate IPv6 packets inside IPv4 packets for transit across IPv4-only networks. Now largely deprecated in favor of native dual-stack.
NAT64 + DNS64: Allows IPv6-only clients to access IPv4-only servers. NAT64 is a gateway that translates between IPv6 and IPv4; DNS64 synthesizes AAAA records for IPv4-only domains by embedding the IPv4 address in a specific IPv6 prefix. Used heavily in mobile networks where new devices are IPv6-native.
DS-Lite (Dual-Stack Lite): ISPs route customer IPv6 traffic natively but tunnel IPv4 traffic through their network, sharing a smaller pool of IPv4 addresses across many customers. Reduces ISP IPv4 address requirements while delivering IPv6 natively.
Check Your IP Version Right Now
See instantly whether your ISP has assigned you an IPv4 or IPv6 address — and what it reveals about your connection.
Hide My IP NowIPv6 Adoption Progress
IPv6 adoption has accelerated substantially since 2016, driven by mobile networks and major ISPs completing dual-stack deployments. Global IPv6 adoption measured by Google stands at over 45% as of 2026 — meaning nearly half of all connections to Google's services use IPv6.
Leaders in IPv6 deployment:
- Mobile networks: T-Mobile US has over 90% IPv6 traffic. Verizon and AT&T are above 70%. New mobile devices on LTE and 5G networks often get IPv6-only addresses by default.
- Major cloud providers: AWS, Azure, and Google Cloud all support IPv6 natively. Many CDNs accept IPv6 connections at the edge.
- ISPs by region: Belgium, India, and Germany lead among countries with high IPv6 penetration rates exceeding 50-60% of traffic.
Operators that have not deployed IPv6 face increasing costs for IPv4 address space (IPv4 addresses now trade for $40-60 each on the secondary market) and technical debt managing NAT infrastructure. Enterprise IT teams increasingly encounter IPv6 requirements from cloud and mobile-first applications.
Check whether your current connection uses IPv4 or IPv6 with our IP address checker — the format of your IP address instantly tells you which protocol your ISP assigned.
IPv6 Security Considerations
IPv6 introduces new security considerations that network operators must address:
Larger attack surface from SLAAC: Stateless autoconfiguration means devices can obtain addresses without central tracking. A compromised device can be harder to locate. DHCPv6 logging or SLAAC guard features on switches can help maintain visibility.
Rogue Router Advertisements: SLAAC relies on ICMPv6 Router Advertisement (RA) messages. An attacker on the local network can send fake RAs to redirect traffic. RA Guard on managed switches prevents unauthorized devices from sending RA messages.
IPv6 tunnel attacks: Organizations that have not disabled legacy tunneling protocols (6to4, Teredo, ISATAP) may have unmonitored IPv6 traffic bypassing IPv4 security controls. Explicitly disable unused transition mechanisms.
Firewall coverage: Many legacy firewalls were configured only for IPv4 rules. Ensure your firewall policy covers IPv6 — dual-stack hosts are protected only as well as the more permissive of their IPv4 and IPv6 firewall rules.
Privacy extensions: RFC 4941 defines IPv6 privacy extensions that generate temporary random interface identifiers, preventing devices from being tracked by their IPv6 address. Modern operating systems enable this by default. Use our DNS leak test to verify your IPv6 DNS traffic is not bypassing your VPN.
Frequently Asked Questions
Do I need to do anything to start using IPv6?
Probably not — if your ISP supports IPv6 and your router is modern, you may already be using IPv6 without knowing it. Check your current IP with our <a href="/">IP lookup tool</a>. If you see a colon-separated address, you are on IPv6. If you only see an IPv4 address, contact your ISP about their IPv6 rollout timeline.
Is IPv6 faster than IPv4?
Not inherently — IPv6 and IPv4 travel at the same speed. However, with IPv6, your traffic does not need to traverse NAT devices, which can reduce latency slightly. On mobile networks, IPv6 routes are sometimes better-optimized than IPv4 paths, resulting in marginally better performance. Use our <a href="/speed-test">speed test</a> to measure your actual connection performance.
When will IPv4 be turned off?
There is no planned sunset date for IPv4, and it is unlikely to be formally 'turned off' in the foreseeable future. The industry is moving toward IPv6 gradually over decades. IPv4 will remain operational for legacy systems for the long-term future, much like how analog telephone networks coexisted with digital for decades.
Why do some services have both A and AAAA DNS records?
An A record maps a domain to an IPv4 address; an AAAA (quad-A) record maps it to an IPv6 address. Dual-stack services publish both so that IPv6-capable clients connect over IPv6 while IPv4-only clients still connect successfully. This is the standard practice for any service that wants to serve all clients regardless of their IP version.
