Why Did Facebook’s Global Outage Happen? Inside the BGP and DNS Failures

Facebook Outage Overview

Facebook restored service after a six‑hour global outage that affected Facebook.com, Instagram, WhatsApp, Messenger and Oculus VR.

“We sincerely apologize to everyone affected by the Facebook service interruption. We encountered network issues, and the team is working to debug and restore as quickly as possible.” – Mike Schroepfer, 2021‑10‑04

Infrastructure Vice President Santosh Janardhan explained that the root cause was a configuration change on a backbone router, which caused traffic between data centers to go out of control and broke Facebook’s internal backbone network.

Technical Reasons

Cloudflare engineers described the role of the Border Gateway Protocol (BGP) in directing Facebook traffic. BGP advertises a network’s routes to other autonomous systems; during the outage Facebook stopped advertising its routes, so ISPs could not find Facebook’s network.

At the same time, Facebook’s DNS records disappeared, preventing domain name resolution for facebook.com.

Experts noted that core internet protocols created in the 1970s‑80s were not designed for today’s scale and are vulnerable to small human errors that can cause massive disruptions.

Data‑Leak Conspiracy Theories

Despite no evidence of a breach, rumors linked the outage to a supposed 1.5 TB data leak advertised on RaidForums. Security analysts pointed out that the data was claimed to be scraped, not obtained through an internal breach, and warned against the spread of such misinformation.