A business needs to create a simulated environment that mimics a production infrastructure to make changes to the OSPF process and analyze the impact. What should be used?

Cisco VIRL and CML allow engineers to deploy virtual routers and switches that replicate a production network topology, including OSPF configurations. Changes to the OSPF process can be applied and their impact analyzed in an isolated virtual environment without affecting live infrastructure.

Cisco DevNet Sandbox provides shared, pre-built lab environments for learning programmability and APIs; it does not allow you to build a custom simulation of a specific production OSPF topology.

pyATS is a Python testing and automation framework used to execute test cases against real or virtual network devices; it does not itself create or simulate a network infrastructure.

Puppet is a configuration management tool that enforces desired state on existing infrastructure; it has no capability to simulate or emulate network devices or topologies.