The correct answer is Air-gapped because this architecture deliberately isolates systems from external and internal networks to prevent any direct electronic communication. In the Security+ SY0-701 domain of Security Architecture, air-gapped environments are used to achieve the highest level of protection against network-based threats by physically or logically separating critical systems from untrusted networks such as the internet or even the organization’s internal network.

In this scenario, the CIO requires that network devices cannot connect to the public internet or the local network for firmware updates, and that updates must be performed manually using a portable device. This is a defining characteristic of an air-gapped architecture. Air-gapped systems rely on controlled, manual transfer methods—such as USB drives or other removable media—to introduce updates, ensuring that malware, remote exploits, and supply-chain-based network attacks cannot reach the isolated systems through traditional network paths.

Option A, Microservices, refers to an application design model where software is built as loosely coupled services and does not address physical or logical network isolation. Option C, Software-defined networking, focuses on centralized and programmable network control, not network disconnection. Option D, Serverless, is a cloud computing model where infrastructure management is abstracted away from developers and is incompatible with isolated, offline environments.

The SY0-701 study guide highlights air-gapped architectures as common in high-security environments such as industrial control systems, military systems, financial infrastructure, and environments requiring maximum protection against zero-day exploits and remote compromise. While air-gapping introduces operational overhead and update delays, it significantly reduces attack surface and exposure to external threats.

In summary, an architecture that requires manual updates via portable media and prevents any direct network connectivity is best described as air-gapped, making option B the correct answer.