Numerous popular websites, apps, and news outlets around the world went down for almost an hour early Tuesday following a failure at Fastly, a major content delivery service.
During the outage, web users – including readers of USA TODAY – received Error messages such as “Error 503 Service Unavailable” when trying to access websites. The outage began just before 6 a.m. EDT and recovery began less than an hour later.
Instead, Fastly cited a technical problem, saying: a fix was appliedthe Associated Press reported.
In one Message posted on Twitter At 7:09 am EDT, Fastly said, “We have identified a service configuration that is causing malfunctions in our POPs worldwide and have disabled that configuration. Our global network is back online.”
Still confused? That means:
What are CDNs?
Fastly is a cloud-based content delivery network, or CDN. Websites, apps, and other businesses use CDNs to move content around the world, reducing access time for users. CDNs carry more than half of the internet trafficsays Akamai, a CDN and cloud services company.
CDNs refer to themselves as internet intermediaries. A simplified version of the process:
- A website wants to serve content such as a webpage, a video or an image and sends it to a CDN.
- The CDN copies the content to edge servers over the network.
- The copying process is known as caching. Cached information can be quickly accessed and is stored on a server for a specified period of time.
- The servers are clustered in strategically strategically placed locations around the world. They are known as points of presence or POPs.
- When a user searches for content, for example by typing a URL into a web browser, the CDN sends it from the nearest edge server. Imperva.com says an appropriate PoP will be selected based on regional internet traffic patterns.
CDNs say the benefits are:
- A reduction in the physical distance for a content request.
- Less time between requesting a web page and loading the page on a device.
- A reduction in bandwidth costs.
How do CDNs work?
Let’s see how this works using the USA TODAY website or app, where you can see this story in a simplified example:
Some joke that the internet is a series of tubesbut that’s pretty much accurate. There are wires in tubes everywhere that connect physical computers to form the network.
You, the user or customer, submit a request to download a file. It could look like a URL that you type into a web browser. Or the link you clicked that brought you to this page.
A website is usually a collection of files that your computer must download from a server.
In our simple example, your request goes up to a Web server, a machine that sits somewhere. We used to rely on physical racks in our server room in the basement. Most of our servers are virtual now, but we’ll save an explanation of virtualization and cloud infrastructure for another day.
This web server is ours Origin server, where the files came from.
If the request is valid, the server will make these files available to you. Your computer downloads them while the data is being sent to your computer over the Internet.
However, files can be large and your computer can be physically far from the server. And you might want to request a website or file over and over again, and downloading it repeatedly is slow and costly.
This is where caching comes in. It’s a concept of saving the last-seen copy of a file or data item for easy retrieval.
You can think of it as layers of onions protecting the central programs and computers from too much stress.
One of the most important forms of caching is the content delivery network.
A content delivery network is what it sounds like: a collection of thousands of web servers that store the latest copies of websites, files, and application data so users can download files and get things done faster.
Companies like Akamai and Fastly maintain thousands of edge servers at points of presence around the world. These are close by, even on cell towers. And as soon as a person visits a version of a website, they save a copy there for all subsequent users.
So, if you’re not the first person to read this USA TODAY article, it’s likely being served to you by an edge server in a CDN.
In an event like today’s outage, some edge servers or the entire CDN may become inoperable and everyone must return to the origin server. This leads to major bottlenecks as the servers become overloaded. Meanwhile, engineers are rushing to react to the flow of traffic and stabilize systems.
Examples of websites affected by the outage
USA TODAY, New York Times, CNN, Guardian, BBC, Financial Times, Le Monde
Youtube, Instagram, Twitter, HBO Max, Reddit, Spotify, Twitch, Stack Overflow, Hulu, Quora, Vimeo, Stripe
Amazon, PayPal, Shopify, Etsy
SOURCE USA TODAY Network Reporting and Research; Associated Press; Reuters; Fastly.com; Akamai; imperva.com
Mitchell Thorson and Katie Vogel contributed to this report.
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Published June 9, 2021 at 12:59 p.m. UTC
Updated June 9, 2021 at 03:13 UTC