Thousands of sites down around the world, what happened

Here's why for almost two hours thousands of Internet sites went offline and why it could happen again.


Giuseppe Croce Journalist

Peppe Croce, journalist since 2008, deals with electronic devices and new technologies applied to the automotive world. He joined Libero Tecnologia in 2018.

At first, it seemed to many a down of their phone operator, with the inability to connect to almost any website. Then it became clear that the connection had nothing to do with it: it was the sites themselves that weren't working. Thousands of sites, both in Italy and abroad: from Corriere della Sera to Gazzetta dello Sport, in Italy, from New York Times to Financial Times, abroad.

What happened? A technical problem, lasting about a couple of hours, at Fastly. That is to one of the biggest CDN in the world. Among the illustrious "victims" there are also Reddit, Spotify, Stack Overflow and even the American site of Amazon (the Italian one continued to work properly). None of the sites involved could do anything: only wait for the problem to be solved and, consequently, for their site to come back online. In the meantime, however, hundreds of millions of Internet users continued to be unable to connect to thousands of Web sites, receiving error messages such as "I/O Error" or "Error 503 - Service Unavailable".

Internet Down: how many sites affected

According to the Wall Street Journal, which cites data provided by Kentik, about 75% of the Internet traffic normally handled by Fastly collapsed. This translates into thousands and thousands of sites down worldwide, starting at 11:30 a.m. Italian time and ending at 1 p.m.

Among the most popular sites that went KO due to the collapse of Fastly's CDN are The New York Times, The Guardian, CNN, BBC, Amazon America, Reddit, (the official website of the British government), Spotify, Twitch and even a piece of Twitter: the one that handles emoji.

What is a CDN

Fastly is a CDN service: Content Delivery Network. It's a type of server network that hosts the content (or part of the content) of other sites in order to make its distribution faster and more efficient.

When a site needs to be accessible quickly from all over the world, in fact, it's not useful to keep all the data on a single set of servers, in a single country. This is because that country may be far away from the user's country. That's why you use CDNs, which distribute content to servers closer to the user.

This system greatly improves performance in two specific cases: when you need to send large files to users (this is the case of streaming platforms, such as Twitch), or when you need to deliver the same content to many users at the same time (this is the case of large online newspapers, which are viewed by hundreds of millions of readers from all over the world).

Using a CDN is therefore an advantage almost always, but today's episode shows the real big limitation of this content distribution system: if the CDN goes down your site collapses and you can't do anything about it.