The basic difference
IPv4 and IPv6 are versions of the Internet Protocol, the addressing and routing system that lets packets travel between networks. IPv4 uses 32-bit addresses. IPv6 uses 128-bit addresses and was designed with an address space large enough for the internet’s continued growth.
| Feature | IPv4 | IPv6 |
|---|---|---|
| Address length | 32 bits | 128 bits |
| Written as | Four decimal numbers | Hexadecimal groups |
| Example | 203.0.113.24 | 2001:db8::24 |
| Address supply | About 4.3 billion total combinations | A vastly larger space |
How the address formats differ
An IPv4 address has four decimal values from 0 to 255 separated by dots. Each value represents eight bits, producing 32 bits in total.
An IPv6 address is written as eight groups of hexadecimal digits separated by colons. Leading zeroes within a group can be omitted, and one consecutive run of all-zero groups can be compressed to ::. That is why valid IPv6 addresses can look different in length even though each represents 128 bits.
Why IPv6 was needed
IPv4’s address space sounded enormous when the protocol was designed, but the internet eventually connected far more people, services, and devices. Conservation techniques extended its life. Private address ranges and NAT let many devices share one public IPv4 address. Providers can also share public IPv4 addresses across customers.
IPv6 replaces address scarcity with a much larger space. It also supports modern network configuration and routing without relying on the same address-sharing pattern. Deployment takes time because networks, applications, security tools, and support processes all need to handle the newer protocol correctly.
Why your device may have both addresses
Many networks use dual stack, which means IPv4 and IPv6 operate at the same time. When a service is available over IPv6 and the path works, the device may choose IPv6. It can still use IPv4 for destinations or networks that do not support IPv6.
Other transition systems carry one protocol across infrastructure built for the other or translate between them. The result for an everyday user is usually automatic: the operating system and network choose a working route.
NAT, direct addressing, and reachability
Home IPv4 networks commonly use private addresses behind Network Address Translation. That lets many devices share the router’s public IPv4 address. IPv6 generally gives interfaces globally unique addresses, though networks still use firewalls to control inbound traffic.
A globally unique address does not mean a device is automatically open to the internet. Reachability depends on router and firewall policy. Conversely, NAT should not be treated as a complete security system; filtering and secure service configuration remain important.
Privacy and security with IPv4 and IPv6
Both protocols expose an internet-facing source address to services you contact. Neither address alone normally identifies an exact person or street address, though it can contribute to approximate location, abuse prevention, analytics, and session risk signals.
Modern systems can use temporary IPv6 interface identifiers for outbound connections so one stable hardware-derived suffix is not presented indefinitely. Networks still keep operational logs, and websites can recognize users through many signals beyond an IP address.
Security practices apply to both versions. Keep firewalls configured, patch devices, avoid exposing unnecessary services, and remember to include IPv6 in monitoring and access rules. An organization that filters only IPv4 may leave an unintended IPv6 path untreated.
How to tell which version you are using
The View My IP lookup labels the direct address as IPv4 or IPv6. A dotted decimal value is IPv4. A colon-separated hexadecimal value is IPv6.
Seeing one version on a website does not prove your device lacks the other. DNS, browser connection logic, VPN support, provider routing, and the website’s own configuration all affect which route is selected. If everything works, you usually do not need to prefer one manually.