Cisco CCNA glossary of networking, routing, switching terms, traps, and decision cues.
Use this glossary when Cisco Certified Network Associate (CCNA) terms start to blur together. The goal is practical recognition, not encyclopedia coverage.
| Term | Exam meaning |
|---|---|
| VLAN | Layer 2 broadcast domain segmentation. |
| Trunk | Link carrying traffic for multiple VLANs. |
| OSPF | Link-state routing protocol used inside an organization. |
| ACL | Access control list that filters traffic based on rules. |
| NAT | Network address translation between address spaces. |
| Controller | System that centralizes network management or automation decisions. |
| Pair | How to separate them |
|---|---|
| Network fundamentals vs IP connectivity | Ask which layer the scenario is testing, then match the answer to that layer only. |
| Control vs evidence | A control changes behavior; evidence proves behavior or supports investigation. |
| Managed service vs custom build | Managed services win for lower operational effort unless the requirement needs unsupported customization. |
| Prevention vs detection | Prevention blocks or reduces a bad event; detection finds or reports that it happened. |
Do not memorize terms in isolation. For each term, write one scenario where it is the best answer, one scenario where it is a distractor, and one signal that proves it worked.