The Border Gatway Protocol is what network providers use to announce which IP ranges they can route traffic for. The problem is it's almost totally unauthentica

The Border Gatway Protocol is what network providers use to announce which IP ranges they can route traffic for. The problem is it's almost totally unauthenticated, so rogue ISPs and network operators can suddenly take over parts of the internet by "leaking" routes for ranges they shouldn't be able to control. They do this by announcing something like "send me all traffic for 1.1.1.1 - 1.1.1.255", and if their peers don't verify it, they'll just start routing that traffic to them. Peer by peer, the route then propagates and a larger portion of the internet, and as routers learn the new bad route, more of the traffic to those IPs gets sent to incorrect network.