After Facebook, and subsidiaries Instagram and Whatsapp, all experienced downtimes on Monday, people not familiar with the situation suggested that the outage was the result of a cyberattack. In an official statement the company blamed “configuration changes on the backbone routers that coordinate network traffic between our data centers” which interrupted communication and had downstream effects. Experts suggested from the beginning of the outage that an issue with the company’s Domain Name System which allows connected devices to locate one another was the problem.
Source: https://www.cyberscoop.com/is-facebook-down-instagram-outage-whatspp/
