A user reports a Linux server is running slowly. Which of the following tools is an administrator MOST likely to use to check server performance?

The `top` command displays a continuously updated summary of system resource utilization - including per-process CPU and memory usage, system load averages, and total resource consumption - allowing an administrator to immediately identify which processes are responsible for degraded performance. It supports interactive sorting and filtering so the heaviest resource consumers can be isolated quickly. It is the most direct and widely used tool for real-time Linux performance triage.

MRTG (Multi Router Traffic Grapher) is a network traffic graphing tool designed to visualize bandwidth utilization over time, not to diagnose CPU or memory performance on a local server.

VNC is a remote desktop protocol that provides graphical access to a server's desktop environment - it is a remote access tool, not a performance monitoring utility.

netstat reports on network connections, routing tables, and socket statistics, which is useful for network-layer diagnostics but provides no information about CPU load, memory pressure, or process-level resource consumption.