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Network Case Files

Real network mysteries, and how they were solved.

Each case links to the engineer's own write-up. Our short summary gives the symptom and how the investigation began. The answer is left for the original.

Each dot is a case, placed by year and by the layer where the root cause sat. Choose a layer to filter the list.

Cases

1 case

A department couldn't send email farther than about 500 miles

The case of the 500-mile email, ibiblio.org, 2002

Added 13 Nov 2026

The chairman of a university statistics department called to say that email could not be sent farther than about 500 miles, and that his staff had drawn a map to prove it. The administrator was sure email does not work that way. Then he sent test messages to servers at different distances and found the same boundary. The story follows how he worked out why distance could matter to a mail server, down to a calculation that explains the number itself.

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