The Day Facebook Went Offline: A Case Study in Centralization

In October 2021, Facebook disappeared from the internet for roughly six hours. Its core platforms — Instagram and WhatsApp — went down with it. For many users it felt like an unusually long outage. For businesses, it meant lost revenue. For engineers, it exposed something more structural: how centralized modern internet infrastructure has become. This wasn’t a breach. It wasn’t ransomware. It wasn’t a nation-state attack. It was a routing failure. What Actually Happened The root cause was a configuration change affecting BGP (Border Gateway Protocol). BGP is how networks announce their IP prefixes to the rest of the internet. When Facebook’s routes were withdrawn, its IP space effectively disappeared from global routing tables. No routes → no traffic. DNS servers became unreachable. Domain names stopped resolving. Internal tools that relied on the same infrastructure went down. Even physical access systems reportedly failed because they depended on the internal network. This is a criti