What topology does the internet use?

Answer 1

The internet uses a very complex topology, due to the massive number of nodes and the high redundancy that is characteristic of high availability systems like the internet. Different parts of the internet look like different topologies. The internet would be best approximated as a mesh topology.

For an image of a simple mesh topology, and a discussion of the different possible network topologies, see the wikipedia article in the links below.

Answer 2

physical ring topology with all nodes connected to one another