A botnet topology is the network structure by which botnet interconnections are organized.
Typical botnet topologies include:
- Star, in which the bots are organised around a central C&C server.
- Multi-server, in which there are multiple C&C servers for redundancy in case one is disabled.
- Hierarchical, in which multiple C&C servers are organized into tiered groups to increase reliability. The hierarchical structure also makes it possible to parcel out groups of bots for rental to different clients, and reduces the number of machines that could be discoverable from the detection of a single group or bot.
- Random, in which there is no C&C server at all and bots communicate peer-to-peer (P2P botnet), with more advanced botnets using encryption.
As a resiliency measure, some non-random botnets are designed to reorganize as a P2P botnet in the event that a C&C server is taken down.