I didn’t see this mentioned yet, but IP ranges are normally assigned by generic location, so each of thes routers routing to the next one (hops) basically have a memory table from prior routes/configured by ISPs to say “this is the best current upstream router to route to for this destination”. They also store the distance between routers and aim for the smallest distance. this is how they are fast and is called routing tables.
Routing tables can be misconfigured causing major outages and old routers used to be able to only store a smaller table so 512k day happened. We already passed the next one 768k though ISPs mostly had their crap together for that one.
I didn’t see this mentioned yet, but IP ranges are normally assigned by generic location, so each of thes routers routing to the next one (hops) basically have a memory table from prior routes/configured by ISPs to say “this is the best current upstream router to route to for this destination”. They also store the distance between routers and aim for the smallest distance. this is how they are fast and is called routing tables.
Routing tables can be misconfigured causing major outages and old routers used to be able to only store a smaller table so 512k day happened. We already passed the next one 768k though ISPs mostly had their crap together for that one.