Category Archives: Cloudflare

04Oct / 2021

How Facebook disappeared from the internet

Cloudflare describes how things looked from their point of view the day that Facebook, along with its other properties, went down. From the Border Gateway Protocol, which defines routing information:

A BGP UPDATE message informs a router of any changes you’ve made to a prefix advertisement or entirely withdraws the prefix. We can clearly see this in the number of updates we received from Facebook when checking our time-series BGP database. Normally this chart is fairly quiet: Facebook doesn’t make a lot of changes to its network minute to minute.

But at around 15:40 UTC we saw a peak of routing changes from Facebook. That’s when the trouble began.

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Posted by in Cloudflare, Facebook, Statistical Visualization

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15Jan / 2021

Random number generation with lava lamps

Tom Scott explains how Cloudflare uses a wall of lava lamps to generate random numbers. A video camera is pointed at the wall, and the movement in the lamps plus noise from the video provides randomness, which is used to secure websites.

Even though computers can do many things on their own, they still need help from the physical world for true unpredictability. The robot overlords aren’t here yet. [via kottke]

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Posted by in Cloudflare, lava lamp, randomness, statistics, Tom Scott

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