ALL types of networks LAN/WAN/MAN and SAN.... this is simply a preference as tp how you would like it to be set up.
Star topology is very common; chances are any company you can think of (big or small) is using a star in their LANs somewhere within the company.
Star topology.
Star Topology
The most common LAN topology is that of a "star." In a star topology, each computer, or "node", is connected to a central hub. This is more reliable than a more classical "ring" topology, because a node failing will not bring down the entire network. A bus topology is arguably more reliable, but has poorer performance.
No one knows, since this is not published information. Companies are not likely to publish anything about their network topology, since it may be considered a security risk.
The "star" topology is the most common.
Star Topology, where Hubs can act as repeaters.
Star topology
Star topology is one of the oldest topology
bus topology.
cat5, cat6, utp, stp cables etc.
There are number of LAN technologies and each technology is classified into a category according to its topology , two such topologies are star and ring topology. In star topology ,The hub accepts data from a sender and delivers it to receiver, there is no security in star topology . In Ring topology Computers are connected in a circle- the first computer is cabled with the second computer.