What caused the massive Facebook outage?

In a shock to social media devotees everywhere — which is to say, most of us — Monday morning saw Facebook and its major subsidiaries, including Instagram and WhatsApp, out of service.

Initially the cause was traced to a failure in Facebook's Domain Name System (DNS), the program that reads URLs, like govtech.com, as IP addresses and allows your computer to reach the right website, according to ArsTechnica.

Later in the day, Facebook users identified that all of the site's Border Gateway Patrol (BGP) routes had been pulled, which rendered Facebook's DNS servers — and those of Instagram and WhatsApp — unreachable. One user, who reports to be a Facebook employee, said on Reddit that the problem was most likely caused by a faulty system configuration change that was pushed out just before the reported outage Monday.

While the social giant will likely make a formal release about the downtime when a concrete root cause is available, one thing is clear: Someone at Facebook HQ is having a very bad day.