Millions of people were unable to access Facebook, Instagram and WhatsApp for more than six hours on Monday, underscoring the world’s reliance on the platform owned by the Silicon Valley giant.
But what exactly caused the outage?
What does Facebook say?
In an apologetic blog post, Facebook’s vice president of infrastructure, Santosh Janardhan, said that “a configuration change on the Backbone router that coordinates network traffic between our data centers has caused issues disrupting this communication”.
Can you explain it in plain english?
Cyber experts believe the problem boils down to something called BGP, or Border Gateway Protocol—the system the Internet uses to choose the fastest route to move packets of information around.
Sami Slim of data center company Telehouse compared BGP to “the Internet equivalent of air traffic control”.
In the same way that air traffic controllers sometimes change flight schedules, “Facebook updated these routes,” Slim said.
But there was a critical error in this update.
It’s not yet clear how or why, but Facebook’s router essentially sent a message across the Internet that the company’s servers no longer existed.
Why did it take so long to fix the problem?
Experts say Facebook’s tech infrastructure is unusually dependent on its systems – and that proved disastrous on Monday.
After Facebook sent out a fatal routing update, its engineers were locked out of the system, which would have allowed them to tell that the update was in fact an error. So they could not solve the problem.
“It’s generally not a good idea to put all your eggs in one basket,” said Pierre Bonis of AFNIC, the organization that manages domain names in France.
“For security reasons, Facebook has had to focus a lot on its infrastructure,” he said.
“It streamlines things on a daily basis — but because everything is in one place, when there’s a problem in that place, nothing works.”
The knock-on effects of the shutdown included some Facebook employees unable to enter their buildings because their security badges were no longer working, further slowing the response.
Is this unprecedented?
Social media outages aren’t uncommon: Instagram alone has experienced more than 80 in the past year in the United States, according to website builder ToolTester.
However, this week’s Facebook outage was rare in its length and scale.
There is also an example of BGP’s interference at the root of the social media shutdown.
In 2008, when a Pakistani Internet service provider was trying to block YouTube for home users, it inadvertently shut down the global website for several hours.
And the impact of the outage?
The DownDetector tracking service said that among Facebook, Instagram, WhatsApp and Facebook Messenger, “billions of users have been affected by the services going completely offline”.
Facebook, whose shares fell nearly five percent due to the outage, insisted that “there is no evidence that user data was compromised as a result of this downtime”.
But even though it lasted only a few hours, the impact of the bandh remained deep.
Facebook’s services are vital to many businesses around the world, and users complained of being cut off from their livelihoods.
Facebook accounts are also commonly used to log into other websites, which faced additional problems due to the company’s technical slowdown.
Meanwhile rival instant messaging services have reported that they have benefited from the downing of WhatsApp and Facebook Messenger.
Telegram moved from the 56th most downloaded free app in the US to fifth place, according to monitoring firm SensorTower, while Signal tweeted that “millions” of new users had joined.
Among the more curious side effects, many domain name registration companies list Facebook.com as available for purchase.
“There was no reason to believe that Facebook.com would actually be sold as a result, but it’s fun to consider how many billions of dollars it could bring to the open market,” said cybersecurity expert Brian Krebs.
(Except for the title, this story has not been edited by NDTV staff and is published from a syndicated feed.)