Address formats, speed, security, NAT, compatibility, and what proxy users need to know about the longest protocol migration in internet history.
April 12, 202616 min readIPv4 and IPv6 are two versions of Internet Protocol — the system that assigns a unique address to every device connected to the internet. IPv4 has been the backbone of the internet since 1981. IPv6 is its replacement, designed to solve IPv4’s biggest problem: we ran out of addresses.
IPv4 addresses look like this: 192.168.1.1 or 203.0.113.42. Four groups of numbers, separated by dots. There are roughly 4.3 billion possible addresses.
IPv6 addresses look like this: 2001:0db8:85a3::8a2e:0370:7334. Eight groups of hexadecimal digits, separated by colons. There are 340 undecillion possible addresses — that’s a 3 followed by 38 zeros. Enough for every grain of sand on Earth to have trillions of IPs.
In 2026, both protocols run simultaneously across most of the internet. Your device almost certainly uses both without you knowing. Here’s how they compare, what changed, and why it matters for everything from browsing speed to proxy usage.
The most obvious difference is the address format itself.
An IPv4 address is 32 bits long, written as four decimal numbers (called "octets") separated by dots. Each number ranges from 0 to 255:
8.8.8.8 — Google’s public DNS server192.168.1.1 — your home router (private IP)104.26.10.78 — a typical web server32 bits gives exactly 232 = 4,294,967,296 possible addresses. That sounded infinite in 1981. It didn’t last.
An IPv6 address is 128 bits long, written as eight groups of four hexadecimal digits (0–9 and a–f), separated by colons:
2001:4860:4860:0000:0000:0000:0000:8888 — Google’s public DNS in IPv62001:4860:4860::8888 (leading zeros and consecutive zero groups get compressed with ::)128 bits gives 2128 = roughly 3.4 × 1038 possible addresses. To put that in perspective: if you assigned one IPv6 address per nanosecond, it would take over 10 billion years to use them all.
The format looks complex, but you rarely type IPv6 addresses manually. DNS handles the translation (you type google.com, not the IP), and operating systems pick the right protocol automatically.
The internet was designed in the early 1980s for a few thousand academic and military computers. No one anticipated smartphones, IoT devices, cloud servers, or the fact that 5.5 billion people would be online by 2026.
The exhaustion happened in stages:
The workaround that kept IPv4 alive is NAT (Network Address Translation). Your router takes one public IPv4 address from your ISP and shares it across every device in your home. From the outside, your laptop, phone, tablet, smart TV, and IoT thermostat all appear as one IP. This is why you have both a public IP and a private IP.
NAT worked, but it introduced complexity: port forwarding headaches, peer-to-peer connection issues, and a growing dependence on CGNAT (Carrier-Grade NAT) where ISPs share one public IP across multiple households.
The short answer: slightly, yes. But not for the reason most people think.
IPv6 doesn’t have a higher maximum bandwidth. The speed difference comes from two architectural improvements:
With IPv4, every packet that leaves your home network passes through NAT in your router. The router rewrites the source IP and port, maintains a translation table, and reverses the process for incoming packets. This adds a small amount of latency — typically 1–3 milliseconds per hop.
IPv6 eliminates NAT entirely. Every device gets its own globally-unique address, so packets go directly from source to destination without rewriting. For most web browsing, the difference is negligible. For real-time applications (gaming, video calls, VoIP), removing even 2–3ms of latency matters.
IPv4 packet headers are variable-length (20–60 bytes) with optional fields that routers must inspect. IPv6 headers are fixed at 40 bytes with a streamlined structure. Routers process IPv6 packets faster because they don’t need to handle variable-length options.
In practice, Facebook, Google, and Akamai have all published data showing IPv6 connections are 10–15% faster on average than IPv4 connections to the same servers. Apple reported that IPv6 connections to their services are 1.4x faster than IPv4. The difference is most noticeable on mobile networks, where CGNAT adds extra hops to IPv4 traffic.
In IPv4, any router along the path can fragment a packet if it’s too large for the next link. The receiving device then has to reassemble the fragments. This adds latency and increases the chance of packet loss.
In IPv6, routers never fragment packets. Instead, the sending device discovers the maximum packet size for the entire path (called Path MTU Discovery) and sizes packets correctly from the start. This eliminates reassembly overhead and reduces retransmissions.
IPv4 was created before internet security was a concern. Encryption, authentication, and integrity checking were all bolted on later through protocols like IPsec, SSL/TLS, and VPNs.
IPv6 was designed with IPsec as a core feature. In the original IPv6 specification (RFC 2460), IPsec support was mandatory for every IPv6 implementation. This means:
In practice, IPsec adoption in IPv6 has been slower than hoped. Most websites still rely on TLS (HTTPS) for encryption regardless of the IP version. But the architectural advantage is real: IPv6 makes end-to-end encrypted communication simpler and more reliable.
One security consideration: because IPv6 gives every device a globally-unique address, it’s theoretically easier to track individual devices across the internet. IPv6 addresses originally included the device’s MAC address (called EUI-64), which would be a privacy nightmare. Modern operating systems now use privacy extensions (RFC 8981) that generate randomized temporary IPv6 addresses, rotating them regularly to prevent tracking.
The IPv4-to-IPv6 transition has been the slowest migration in internet history. Here’s where things stand in 2026:
Most networks run both protocols simultaneously ("dual-stack"). Your device has both an IPv4 and an IPv6 address. When you connect to a website:
You can check whether your connection supports IPv6 by visiting our IP lookup tool — it shows both your IPv4 and IPv6 addresses if your ISP provides dual-stack. You can also run a dedicated test at our IPv6 checker.
Most of the internet works fine on IPv6 in 2026, but some things still cause issues:
| Feature | IPv4 | IPv6 |
|---|---|---|
| Address length | 32 bits | 128 bits |
| Address format | Dotted decimal (192.168.1.1) | Hexadecimal colons (2001:db8::1) |
| Total addresses | ~4.3 billion | ~340 undecillion |
| NAT required | Yes (essential since 2015) | No (every device gets a public IP) |
| Header size | 20–60 bytes (variable) | 40 bytes (fixed) |
| IPsec | Optional add-on | Built-in |
| Fragmentation | Routers can fragment | Only the sender fragments |
| Broadcast | Yes | No (uses multicast instead) |
| Auto-configuration | DHCP required | SLAAC built-in (+ optional DHCPv6) |
| Global adoption (2026) | ~100% (legacy support) | ~48% of internet traffic |
| Proxy availability | Universal — all providers | Limited — niche use cases |
If you use proxies for web scraping, account management, ad verification, or any other task, the IPv4/IPv6 distinction directly affects your setup. Here’s what matters:
Almost all commercial proxy traffic in 2026 still runs over IPv4. The reasons:
When you buy rotating residential proxies at $2.75/GB, static residential proxies at $3.90/day, or LTE mobile proxies at $2/IP, you’re getting IPv4 addresses. This is the right choice for 99% of use cases.
IPv6 proxies exist, and they serve specific use cases:
The catch: many websites block or throttle IPv6 traffic from known datacenter ranges, and IPv6 residential proxies are extremely rare because most residential routers still prioritize IPv4 for outbound proxy connections.
Connect through your proxy, then visit spyderproxy.com/tools/ip-lookup. The tool shows:
You should also run a WebRTC leak test and a DNS leak test to make sure your real IP isn’t leaking through browser APIs that bypass the proxy.
If you’re on a home connection in 2026, there’s a decent chance your ISP is putting you behind CGNAT (Carrier-Grade NAT) — a giant NAT device that shares one public IPv4 address across dozens or hundreds of households.
CGNAT causes real problems:
IPv6 eliminates all of these problems. Every device gets its own public address, no NAT needed, no port sharing, no CGNAT. This is why the speed improvement from IPv6 is most noticeable on mobile networks (which use CGNAT heavily) and in countries with high CGNAT deployment.
If you’re experiencing unexplained CAPTCHAs, IP bans, or slow connections, checking whether you’re behind CGNAT is worth investigating. Your ISP can tell you, or you can compare the public IP shown by our IP lookup tool with the WAN IP on your router — if they don’t match, you’re behind CGNAT.
It won’t — at least not in the foreseeable future. Here’s why:
The realistic timeline: IPv4 will be "legacy but supported" through at least 2035. IPv6-only networks will become more common on mobile carriers first (T-Mobile US is already IPv6-only with NAT64 for IPv4 compatibility), then gradually on fixed broadband. Full IPv4 sunset is likely a 2040s event.
Here are the quickest ways to check what your connection supports:
curl -4 ifconfig.me — forces IPv4, shows your IPv4 addresscurl -6 ifconfig.me — forces IPv6, shows your IPv6 address (fails if your ISP doesn’t support IPv6)nslookup google.com — if you see both Address: 142.250.x.x (A record) and Address: 2607:f8b0:... (AAAA record), your DNS resolver supports both.If your ISP doesn’t provide IPv6, don’t worry — you’re not missing out on any websites. Every site that supports IPv6 also supports IPv4 (they have to, since half the internet is still IPv4-only). You’re just potentially missing the slight speed improvement from avoiding NAT.
Architecturally, yes. IPv6 has a larger address space, built-in security, no NAT overhead, and simplified packet processing. In day-to-day browsing, the difference is minor because dual-stack handles everything automatically. The biggest practical benefit is avoiding CGNAT-related issues.
Usually by 10–15%, mostly because it bypasses NAT and CGNAT overhead. On mobile networks where CGNAT is heaviest, the improvement can be larger. For raw bandwidth (download speed), IPv4 and IPv6 are equivalent.
Yes, this is called "dual-stack" and it’s how most modern networks work. Your device has both addresses and uses whichever one connects fastest for each connection.
Not strictly, but IPv6 eliminates NAT-related issues that cause "Strict NAT" or "Type 3 NAT" problems in online gaming. If you’re experiencing connection issues in multiplayer games, enabling IPv6 (if your ISP supports it) often helps.
Generally, no. Disabling IPv6 removes the speed benefits and can actually cause slowdowns because your browser still tries IPv6 first (per Happy Eyeballs), then waits for it to fail before falling back to IPv4. The only reason to disable it is if a specific application has a known IPv6 bug.
IPv4 for almost everything. All websites support IPv4, geo-location databases are more accurate for IPv4, and fraud detection is calibrated for IPv4 addresses. Use IPv6 proxies only for specialized high-volume scraping where you need millions of unique IPs. SpyderProxy’s residential, static residential, and LTE mobile proxies all use IPv4.
CGNAT is Carrier-Grade NAT — your ISP shares one public IPv4 address across multiple households. To check: compare the IP shown by our IP lookup tool with the WAN IP on your router’s admin page. If they’re different, you’re behind CGNAT.