I will suggest you to first, tell the uses of Puppet Catalog.
When configuring a node, Puppet Agent uses a document called a catalog, which it downloads from a Puppet Master. The catalog describes the desired state for each resource that should be managed, and may specify dependency information for resources that should be managed in a certain order.
If your interviewer wants to know more about it mention the below points:
Puppet compiles a catalog using three main sources of configuration info:
• Agent-provided data
• External data
• Puppet manifests