The Cluster Manager web UI has three possible agent status types: OK, Error, and In Penalty Box.
indicates the agent is running and connected to the Cluster Manager
indicates the agent has a problem connecting to the Cluster Manager
indicates the agent failed and was not used for the build. The build will attempt to re-use the agent for later builds. If a build job causes an agent failure, that agent is placed in "penalty" status for 30 seconds. This prevents the agent from being reassigned to another build job during that time. The intent is to prevent an agent that has a fatal hardware failure from being repeatedly reassigned to build jobs and then causing multiple (successive) failures, which would eventually cause the entire build to fail.