Whether you’re responsible for a small branch office or a globally distributed enterprise, your ability to see what’s happening on the network determines how quickly you can respond to problems. Network monitoring is more than a single dashboard—it’s an ecosystem of protocols, tools, and practices that help you maintain uptime, enforce service-level agreements, and detect anomalies before they become outages. In this chapter, we’ll build on the foundations laid in earlier chapters by examining the protocols and platforms used to collect data, the metrics that describe performance, and the logging systems that turn raw events into actionable insight.