Which of the following would a systems administrator follow when upgrading the firmware of an organization’s router?

A maintenance window is a pre-approved period of time during which system changes, such as firmware upgrades, can be performed with minimal disruption to operations. Following a maintenance window ensures that the upgrade is planned, communicated, and executed during a time when impact is least significant, reducing potential downtime or service interruptions. The software development life cycle (SDLC) is a process for developing software, not for upgrading hardware firmware. Risk tolerance defines the acceptable level of risk, but doesn't dictate the procedure for an upgrade. A certificate signing request (CSR) is used to obtain an SSL/TLS certificate, unrelated to firmware upgrades.