A mobile intelligent agent is used in a Byzantine fault-tolerant computing network. The mobile intelligent agent ensures that only a single instance of the mobile intelligent agent performs processing in the processing host. The agent interrogates an environment in the processing host for presence of a sibling mobile intelligent agent or a trace left by a sibling mobile intelligent agent. If a sibling mobile intelligent agent or a trace left by a sibling mobile intelligent agent is detected, further execution by the mobile intelligent agent in the processing host is ended. The agent will then be forwarded onward to find a processing host wherein the agent has not been executed.