Study Cisco CCST Networking infrastructure: diagrams, switch and router roles, ports, status lights, cabling, device access, and basic show commands.
Infrastructure questions test whether you can follow a network diagram and perform basic support tasks safely. You are not expected to design an enterprise network, but you should know what switches, routers, ports, status lights, and management access are for.
| Device | Basic role |
|---|---|
| Switch | connects devices within a LAN and forwards frames |
| Router | forwards traffic between networks |
| Wireless access point | connects wireless clients to the network |
| Firewall | filters traffic based on rules and policy |
| Modem or edge device | connects a site to a provider or upstream network |
| Task | Evidence to gather |
|---|---|
| attach cables from diagram | device labels, port labels, cable type, link lights |
| identify device status | LEDs, interface state, error messages, uptime |
| identify ports | physical label, interface naming, link speed, connected device |
| access device data | console, SSH, management UI, network management system |
| run basic show commands | interface status, route, neighbors, MAC table, version, inventory |
Switching usually handles traffic inside the same LAN or VLAN. Routing moves traffic between networks. If the source and destination are in different IP networks, the default gateway or routing path matters.
When a diagram appears, identify the path before choosing the device:
This prevents common mistakes. A switch may be involved in nearly every office connection, but it is not the device that routes between subnets. A firewall may sit on the path, but not every connectivity failure is a firewall problem.
| Access method | What to remember |
|---|---|
| Console | local physical access for setup or recovery |
| SSH | secure remote command-line management |
| Web UI | browser-based management interface where enabled |
| Network management system | centralized inventory, monitoring, alerts, or configuration view |
Use authorized access only. CCST is an entry-level support exam, so the safer answer is usually to gather evidence, use approved management methods, and escalate when the task requires higher privilege.
| Evidence | What it may indicate |
|---|---|
| link LED off | cable, port, endpoint NIC, power, or disabled interface issue |
| interface administratively down | configured shutdown rather than physical failure |
| high errors or drops | cabling, duplex/speed, congestion, or hardware problem |
| no learned MAC address | endpoint not connected, wrong port, VLAN issue, or inactive device |
| missing neighbor | cabling, protocol disabled, non-Cisco neighbor, or topology mismatch |