The address-space difference
IPv4 uses a 32-bit address field, which provides about 4.3 billion possible values before reservations and special uses are considered. IPv6 uses 128 bits, creating a vastly larger space. The expansion supports internet growth without requiring every deployment to rely on the same address-sharing techniques used to conserve public IPv4.
Address size does not mean one device receives one permanent IPv6 value. Interfaces can have several IPv6 addresses, including link-local and temporary addresses, while networks choose how prefixes and lifetimes are assigned.
How the notation differs
| Property | IPv4 | IPv6 |
|---|---|---|
| Address length | 32 bits | 128 bits |
| Usual notation | Four decimal octets, such as 192.0.2.10 | Hexadecimal groups, such as 2001:db8::10 |
| Local-only examples | RFC 1918 private ranges | Link-local and unique-local scopes |
| Typical current deployment | Native, translated, or private plus NAT | Native, dual stack, or translated |
| DNS address record | A | AAAA |
IPv6 notation allows runs of zero groups to be shortened, which is why the text can look unfamiliar. Tools should normalize and label the address family rather than asking users to count punctuation.
Continue with What is an IP address?, compare it with Public vs private IP addresses, or use How to find public and private IP addresses on Android for the next practical step.
How dual stack chooses a path
A dual-stack network makes IPv4 and IPv6 available together. DNS may return A and AAAA records, and the operating system or application selects a reachable path. Modern connection logic can try paths in a way that avoids waiting too long for one broken family.
As a result, opening two services from the same phone can use different protocols. A public-IP check reports the family used by that check; it does not guarantee that every other app used the same family. Test IPv4 and IPv6 separately when the distinction matters.
The protocol details in this guide follow RFC 3849 — IPv6 Address Prefix Reserved for Documentation and RFC 8981 — Temporary Address Extensions for IPv6; use those primary specifications when you need exact terminology or edge-case behavior.
NAT, translation, and transition networks
Because globally routable IPv4 space is limited, home and carrier networks commonly use private IPv4 plus Network Address Translation. IPv6 was designed with enough space for broad global addressing, though firewall policy still controls reachability.
Providers do not move from one protocol in a single step. They may run dual stack, translate between IPv6-only access networks and IPv4 destinations, or retain carrier-grade IPv4 sharing. The public address you see can therefore reflect a native or translated path.
Why one protocol may be missing or fail
- The provider may not offer that address family on the current access network.
- The router may not request or advertise an IPv6 prefix correctly.
- The destination may publish only IPv4 or only IPv6 records.
- A VPN may carry one family differently or disable one path.
- Firewall or probe filtering may make a test fail even when other traffic works.
Compare Wi-Fi and mobile data, test a known destination for each family, and record the VPN state. Do not interpret one failed ping as proof that the entire protocol is absent.
Performance, privacy, and security
IPv6 is not automatically faster. Either family can have better routing, lower congestion, or fewer translation layers on a given provider. Measure the destination and path that matter instead of assigning a speed advantage from the protocol name.
Neither version creates anonymity. IPv6 temporary addressing can reduce simple long-term correlation of one interface address, but websites and applications have other identifiers, and the network still routes the traffic. Security depends on firewall policy, endpoint updates, application encryption, and sound operations for both protocols.