3 ms·
We resolve arbitrary names with DNS to a global identifier (an IP address), but for routing, what you need is a local identifier (which neighbor router to send
by cesarb 6y ago
We resolve arbitrary names with DNS to a global identifier (an IP address), but for routing, what you need is a local identifier (which neighbor router to send the packet to), which means every router or set of routers would need its own database, and each database would need to know about every host in the world. This is exactly what we have nowadays with BGP, only with networks instead of hosts: every core router or set of core routers has a database which knows about every network in the world, and tells which neighbor AS to send the packet to.
- corty 6y agoAlso, DNS caches are just locally used small subsets. Global lookups are again hierarchical, thats why it is called _domain_ name system. Thats why there are dots in the adresses. Also, DNS lookups are rare compared to IP route lookups, you look at DNS for every connection at most, limited by the TTL for caches. Route lookups happen for every packet.