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WHAT'S YOUR ENGINEERING QUOTIENT?

Problem 2—Each Ethernet device has a 48-bit address (the MAC) that is supposed to be unique. If the MACs are chosen randomly, how many devices can be manufactured before there's a better-than-even chance that two of them have the same MAC?

Answer 2

If you wrote a program to solve the birthday puzzle, then it takes a small amount of trial-and-error to discover that when 20,000,000 devices exist, the probability is roughly 0.5086 that two of them have the same MAC.

Contributor: Dave Tweed

03-02 — NEXT Q&A