The services of these three social media companies have all returned to normal. However, it still leaves a question mark why a company as big as the Facebook Group can be down for more than 6 hours. Vice President of Engineering & Infrastructure at Facebook, Santosh Janardhan finally opened up about the cause of Facebook, Instagram, and WhatsApp downtime. The backbone in question is the network that Facebook built to connect all computing facilities. This backbone network is tens of thousands of miles of fibre optic cable that connects all of Facebook’s data centres. Data traffic between these computing facilities is managed by routers. Periodically, Facebook performs infrastructure maintenance, such as repairing broken cables and updating software on routers. During yesterday’s infrastructure maintenance, Facebook intended to enter a command to check the availability of backbone capacity. However, the command actually cut off their data centre instead. This configuration change causes the server connection from the data centre to the internet to drop. The problem is made worse because as a result, the DNS server cannot communicate with the border gateway protocol (BGP). Since Facebook implements high-security safeguards, physically resetting the system takes a lot of time.
