Interesting read on how the folks at Cloudflare saw Facebook go down last night, and how it impacted traffic on their end.
The Internet is literally a network of networks, and it’s bound together by BGP. BGP allows one network (say Facebook) to advertise its presence to other networks that form the Internet. As we write Facebook is not advertising its presence, ISPs and other networks can’t find Facebook’s network and so it is unavailable.
Apparently this failure not only brought the websites and services down, but als prevented employees from opening doors and entering rooms as all those devices/locks are IoT devices which also rely on DNS to communicate with the proper servers. One (unverified) source even claimed that it was a code review bot that auto-merged the faulty BGP rule.