More specific Internet routes usually win
Routing prefers the more specific announcement, which is ordinarily sensible and is also how hijacks succeed.
Announcing a narrower slice of somebody's address space beats their broader announcement almost everywhere, immediately. It is the mechanism behind most high-profile redirections, and the reason filtering by other operators is what actually limits the damage rather than anything the victim controls.
More on Internet routing
- BGP announces reachability, not truthA claim, not a proof
- BGP hijacking can redirect traffic before applications see itThe points move under the train
- Route leaks can be accidental and disruptiveThe whole motorway down a side lane
- RPKI validates route origins, not the whole pathOnly the first pair of hands is signed for
- Anycast sends one address to multiple placesOne address, many doorsteps
- Route filtering is Internet hygieneWe all drink from the same main