Routing table

Each node needs to keep track of which way to deliver various packages of data, and for this it uses a routing table.

A routing table is a database that keeps track of paths, like a map, and uses these to determine which way to forward traffic.

Assuming that the routing tables are consistent, the simple algorithm of relaying packets to their destination's next hop thus suffices to deliver data anywhere in a network.

Routing tables are also a key aspect of certain security operations, such as unicast reverse path forwarding (uRPF).

[2] In this technique, which has several variants, the router also looks up, in the routing table, the source address of the packet.

If there exists no route back to the source address, the packet is assumed to be malformed or involved in a network attack and is dropped.

In the Internet, the currently dominant address aggregation technology is a bitwise prefix matching scheme called Classless Inter-Domain Routing (CIDR).