Global Routing Table

The Global Routing Table is the set of all Internet address prefixes announced into the Default-Free Zone and therefore all comprise the entirety of the "public Internet". The Global Routing Table does not physically exist anywhere; it is a theoretical construct. The table held in memory of some or all routers in default-free networks will contain all of the Global Routing Table plus any prefixes/routes local to the network.

People often talk about growth of the Global Routing Table because there is a rough relationship between this growth and the need to add memory to routers or replace them with more powerful models. Addressing policy seeks to maintain a rate of growth that is consistent with Moore's law and the need of network operators to space out their capital expenditures on new equipment.

Not all registered addresses appear in the Global Routing Table because there are several IP-based networks that use registered addresses but which do not exchange routes with the public Internet. These may or may not connect to the public Internet.