Pie Chart of IPv4 Address Space by Class

About this example

The original IPv4 addressing scheme divided the ~4.3 billion addresses into five classes (A, B, C, D, E). Class A alone holds half of all IPv4 addresses.

The data

• Class A — 50 % of IPv4 space
• Class B — 25 % of IPv4 space
• Class C — 12.5 % of IPv4 space
• Class D (multicast) — 6.25 % of IPv4 space
• Class E (reserved) — 6.25 % of IPv4 space

Source

RFC 791 (Internet Protocol specification, 1981).

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