Change management is an IT practice that aims to minimize disruptions to IT services while making changes to critical systems and services12.
A change is defined as adding, modifying, or removing anything that could have a direct or indirect effect on services1.
Change management involves planning, testing, communicating, and implementing changes in a controlled and coordinated manner2.
Change management can help prevent network outages and other incidents by ensuring that changes are properly assessed, approved, and documented before they are executed2.
Incident response, on the other hand, is the process of detecting and responding to security incidents, such as cyberattacks or data breaches3.
Incident response focuses on the technical aspects of analyzing and containing an incident, while incident management deals with the broader impact of an incident on the business, such as communications, media handling, escalations, and reporting3.
Standard operating procedure (SOP) is a set of instructions that describes how to perform a routine or repetitive task.
SOPs are useful for ensuring consistency, quality, and compliance in various operations, but they are not specific to change management.
System life cycle is a model that describes the phases of development, operation, and maintenance of a system, such as a software application or a hardware device.
System life cycle can help guide the design, testing, deployment, and improvement of a system, but it does not address the issues of change management, such as minimizing disruptions and risks.
Therefore, the best document for the network manager to create to prevent future network outages caused by firmware upgrades is a change management policy.
Reference:
Change management types | Atlassian
Incident Management vs. Incident Response - What's the Difference? - DZone
10 Top change management best practices | Atlassian
[What is a Standard Operating Procedure (SOP) and How to Write It]