2021 Facebook outage

On October 4, 2021, American social network Facebook and its subsidiaries Messenger, Instagram, WhatsApp, Mapillary, and Oculus became globally unavailable. The outage started close to 12:00 pm Eastern Time and lasted around six hours. The reason is known as the loss of IP routes to the Facebook Domain Name System (DNS) servers.
This is believed to have been caused by a problem with Facebook's Border Gateway Protocol. The outage also reportedly broke internal systems used by Facebook employees.