Experts: Egypt “raised the drawbridge” in mere minutes by forcing country’s providers to make simple changes to router configuration files. 90% of Egypt’s networks were unreachable because they had withdrawn their routing announcements. By refusing to tell other networks how to reach their IP addresses, Egyptian Internet service providers effectively cut off all communication with the Web. The process likely took only minutes, according to BGPmon’s Andree Toonk, founder and lead developer of the open-source tool for monitoring BGP.”]
Source: https://www.csoonline.com/article/2126849/how-egypt-pulled-its-internet-plug.html