Which security design would be most appropriate for protecting a high-value asset in a sensitive facility, such as a nuclear power plant, by isolating it from any network?

Isolating a high-value asset, particularly in a sensitive facility like a nuclear power plant, is paramount for ensuring its security. An air gap is a security design that achieves this isolation by physically disconnecting the asset from any other network, including the internet and internal networks. This means that there are no direct or indirect connectivity paths that could allow external access or cyber threats to reach the asset. By employing an air gap, the risk of intrusion, malware, and external attacks is significantly reduced, making it the most secure and appropriate option for protecting critical systems in such environments.

Other options, like peer-to-peer setups or jump boxes, involve some level of networking that could expose the asset to potential attacks. A guest environment typically allows external users limited access to a network, which contradicts the principle of strict isolation necessary for the protection of high-value assets in sensitive facilities. Hence, the air gap stands out as the ideal solution for ensuring maximum security against external threats.