Network topology
The arrangement of a network's nodes and links, such as bus, star, ring or mesh, which determines where single points of failure sit and how faults spread.
Network topology describes how the devices in a network are connected. The physical topology is the actual layout of cables and equipment; the logical topology is the path data follows. The classic shapes are bus (one shared cable), star (every node wired to a central device such as a switch), ring (each node linked to two neighbours in a loop), mesh (nodes linked to many others, fully or partially) and tree; many real networks are hybrids.
For a security professional, topology is mainly an availability question. A bus fails when its shared cable is cut, and every node on it shares one collision domain, which is why access methods such as CSMA were needed. A star isolates a cable fault to one node but makes the central device a single point of failure. A ring can be disrupted by one break unless it is built with a second, counter-rotating ring. A full mesh gives the most redundant paths at the highest cabling and management cost, which is why partial mesh is common for backbones.
Exam relevance: a scenario may describe a layout and ask which failure it is exposed to, or which design best supports availability. Candidates are expected to link each topology to its single point of failure and to its cost of redundancy.