Internet isolation is a security control that blocks or tightly limits outbound network access from a system under test. In a sandbox, lab VM, or AI evaluation harness, it prevents the tested software, agent, or model from reaching external hosts, APIs, repositories, or command-and-control infrastructure.
This matters because many attacks depend on outbound connectivity. Malware may try to download payloads, exfiltrate data, fetch instructions, or contact a remote operator. In defensive testing, internet isolation helps ensure that risky behavior stays contained and does not affect real services. In AI security, it is especially important when models have tool use, shell access, or automation rights: if the isolation layer is weak, the test environment can cross the boundary from simulation into real network interaction. Effective isolation is usually paired with egress filtering, restricted credentials, and monitoring so that any attempted connection is blocked, logged, and investigated.