The Two Generals Problem: neither general can ever confirm the other is ready to attack. Jim Gray proved it in 1978, and the same limit shapes how databases and networks handle failure.

Squirrels have shut down Nasdaq trading twice. Beavers, cows, and sharks have taken down networks too, but misconfiguration, sabotage, and copper theft cause far more damage than any animal ever has.

In 1986, a network slowdown forced Van Jacobson to invent TCP congestion control. Reno, CUBIC, and BBR mark three different eras of solving that problem.