All of the nodes in a Puppet infrastructure contain a Puppet agent. In a split installation, each component checks in with a Puppetserver, just like any other node managed in the infrastructure. In a monolithic installation, the Puppet agent checks in with itself. Every other node managed by Puppet must use the agent to retrieve a configuration. Because the agent is everywhere, understanding some of the common errors with the agent will be universally useful for troubleshooting. Some of the common causes of a malfunctioning agent are as follows:

• Certificate reuse
• Wrong user context when connecting to the master
• Network connectivity
• DNS alternate name