3 ms·

The author wrote an FAQ several years after the original story that answers most of your questions. https://www.ibiblio.org/harris/500milemail-faq.html https://

• throw310822 1y ago
  Yes I think I had read those FAQ at some point, they're terribly handwavy though. "Should have been 6ms instead of 3 for the ACK to come back? Yes, sorry, it was too boring to add"; "Should it be much more and variable because of the routers in between? Yes sure, I probably pinged them and added up the delays"; "Shouldn't plenty of deliveries have failed for destinations much closer than 500 miles? Yes sure, but that must have been the limit..." Etc.
  • lilyball 1y ago
    The "destinations much closer than 500 miles" was explicitly handled in the story, I don't know why that was even in the FAQ except that the asker failed reading comprehension. > "There are a number of destinations within that radius that we can't reach, either, or reach sporadically, but we can never email farther than this radius."
  • throwaway31131 1y ago
    And there's also this nuance from the article text, "The secret here is the kernel will always round 3ms up to at least one whole tick, 10ms." Interestingly, not covered in the FAQ.
    • unclad5968 1y ago
      If you account for signal propagation speed through copper and the unaccounted ACK, I think the timing actually works out about the same.