Which of the following should be done FIRST before installing NOS patches in a production environment?

Installing patches on non-critical servers in production is still a production deployment and carries risk, which should be mitigated by prior testing in a dedicated test environment.

Installing patches in a test environment first allows administrators to identify and resolve potential compatibility issues or regressions without impacting live production systems. This best practice minimizes risks associated with system downtime or service disruption in a critical production environment.

Installing NOS patches on a PC is irrelevant as PCs run client operating systems, not network operating systems (NOS), and the impact on a single PC does not accurately reflect server environment behavior.

Installing patches directly on critical servers in production without prior testing is a high-risk approach that could lead to widespread service outages if issues arise.