What Is the Difference Between IPv4 and IPv6

Short answer

IPv4 uses 32-bit addresses and supports about 4.3 billion devices. IPv6 uses 128-bit addresses and provides a virtually unlimited supply.

Key differences

• Address space: IPv4 is exhausted; IPv6 solves the shortage.
• Notation: IPv4 uses dotted decimal (192.0.2.1); IPv6 uses hexadecimal (2001:0db8::1).
• Features: IPv6 has built-in security and auto-configuration.
• Compatibility: IPv6 is not backward compatible, so transition mechanisms like dual-stack are used.

When to use each

• IPv4 remains dominant but is increasingly NATed.
• IPv6 is the future and is required for new networks and IoT growth.