Why did Facebook, Instagram and WhatsApp shut down?

Hundreds of millions of people were unable to access Facebook, Instagram and WhatsApp for more than six hours on Monday, underscoring the world’s reliance on platforms owned by the Silicon Valley giant.

But what actually caused the outage? What does Facebook say happened?

In an apologetic blog post, Santosh Janar­dhan, Facebook’s vice president of infrastructure, said that “configuration changes on the backbone routers that coordinate network traffic between our data centres caused issues that interrupted this communication”.

Explaination in simple words

Cyber experts think the problem boils down to something called BGP, or Border Gateway Patrol — the system the internet uses to pick the quickest route to move packets of information around.

Sami Slim of data centre company Telehouse compared BGP to “the internet equivalent of air traffic control”.

In the same way that air traffic controllers sometimes make changes to flight schedules, “Facebook did an update of these routes,” Slim said. But this update contained a crucial error.

It’s not yet clear how or why, but Facebook’s routers essentially sent a message to the internet announcing that the company’s servers no longer existed.