Overkill

absurdly advanced tech, explained badly, used for dumb stuff

All overkills

Routing

or: a phone book run on trust, used to find pizza

When you type a website’s name, your computer asks a chain of servers to turn it into a number, starting from just 13 root names copied onto more than 1,800 machines around the world1. Then tens of thousands of independent networks, many of them owned by companies that compete with each other, tell their neighbors which addresses they can reach, using a protocol first sketched on two lunch napkins in 19892, and they mostly just take each other’s word for it3, and somehow your request finds a path across the planet in a fraction of a second.

And we use it to find a pizza place that closes in ten minutes.

How it works, badly

  1. #
    where’s pizza.com?name in,number out
    Your computer asks the internet’s phone book for a number.
  2. #
    root.com.org.pizzapizza.com13 root names,1,800+ copies
    It starts at the root and works its way down.
  3. #
    net Anet Bnet Ctrust me, I knowthe way to pizza
    Networks tell each other how to get places, on the honor system.
  4. #
    closes inten minutes?!
    Then we use it to find pizza that closes in ten minutes.

Wait, is that real?

Yes, including the napkins.

The phone book↩

The Domain Name System turns names like a website’s into the numeric addresses computers use. At the top sit 13 root server identities, lettered A through M and run by 12 independent organizations. Each identity is copied across many machines; there were more than 1,800 root server instances worldwide as of 2024.

The napkins↩

The Border Gateway Protocol, BGP, is how separate networks tell each other which addresses they can reach. Kirk Lougheed of Cisco and Yakov Rekhter of IBM sketched it over lunch at an Internet Engineering Task Force meeting in 1989, on what became known as the “two-napkin protocol.” It is still the routing protocol of the global internet.

The honor system↩

Networks largely accept what their neighbors announce, so one mistake can spread fast. On October 4, 2021, Facebook withdrew the routes to its own DNS servers; Facebook, Instagram, and WhatsApp were unreachable worldwide for more than seven hours.

The fine print↩

Your computer doesn’t go to the root every time; answers are saved, or cached, along the way, so most lookups never leave your provider. “Tens of thousands of networks” is deliberately loose, because the count keeps growing. And “honor system” is a little unfair: operators increasingly sign their route announcements so others can check them, but plenty still don’t.

Sources: Root Server System; Computer History Museum: the two-napkin protocol; ThousandEyes: Facebook outage analysis

Last fact-checked .