What are the key differences between IPv4 and IPv6 addressing?

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What are the key differences between IPv4 and IPv6 addressing?

Asked on Dec 16, 2025

Answer

IPv4 and IPv6 are both Internet Protocol versions used for addressing and routing traffic across networks, but they differ significantly in structure, capacity, and features. IPv4 uses a 32-bit address space, resulting in approximately 4.3 billion unique addresses, whereas IPv6 uses a 128-bit address space, allowing for a vastly larger number of unique addresses.

Example Concept: IPv4 addresses are written in dotted-decimal format (e.g., 192.168.1.1) and support features like NAT due to address scarcity. IPv6 addresses, written in hexadecimal and separated by colons (e.g., 2001:0db8:85a3:0000:0000:8a2e:0370:7334), eliminate the need for NAT by providing a larger address space. IPv6 also includes improvements such as simplified header format, improved support for extensions and options, and built-in features like address autoconfiguration and mandatory IPsec support.

Additional Comment:

IPv4 supports broadcast addressing, whereas IPv6 uses multicast and anycast addressing.
IPv6 includes built-in Quality of Service (QoS) capabilities through the Flow Label field.
IPv6 addresses are designed to improve routing efficiency and reduce the size of routing tables.
Transition mechanisms like dual-stack and tunneling are used to facilitate IPv4 to IPv6 migration.

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