What is essential to ensure that system changes do not disrupt existing services?

To ensure that system changes do not disrupt existing services, validation is essential. Validation involves testing and verifying that the changes to the system meet the requirements and function as intended before they are fully implemented. This process helps to confirm that the new configurations or updates work correctly within the existing environment and do not introduce unforeseen issues or degrade performance.

By validating changes, organizations can detect potential problems early, allowing for adjustments or troubleshooting before the changes affect users or critical business operations. This proactive approach minimizes the risk of service interruptions and ensures a smoother transition during updates or modifications to the system.

While the other options, like retesting, monitoring bandwidth, and rollback strategies, play important roles in change management, validation is specifically focused on confirming that the new changes will function as expected within the current system context, which is key to avoiding disruptions.