CompTIA N10-009 glossary of addressing, routing, switching, wireless, security, and troubleshooting terms.
Use this glossary when Network+ terms blur together under time pressure. It is a cleanup tool, not a replacement for the lesson pages.
| Term | Short meaning | Fast exam anchor |
|---|---|---|
| AAA | Authentication, authorization, and accounting for access control | prove identity, control permission, log the event |
| APIPA | IPv4 self-assignment in 169.254.0.0/16 when DHCP fails |
local fallback, not normal managed addressing |
| CIDR | Prefix notation like /24 or /64 |
address scope and subnet size |
| FHRP | Default-gateway redundancy method | first-hop availability |
| IDS | Detects suspicious activity | sees and alerts |
| IPS | Detects and can block | sits inline and acts |
| Jitter | Variation in delay | bad for voice and real-time flows |
| MTBF | Mean time between failures | how often failure happens |
| MTTR | Mean time to repair or restore | how quickly service comes back |
| NAC | Network access control based on policy and posture | who can join and under what condition |
| NAT | Address translation at a boundary | internal to external mapping |
| PAT | Port-based NAT for many hosts sharing one address | many-to-one via ports |
| PBQ | Performance-based question | apply, diagnose, configure, or sequence |
| PKI | Certificate and trust-chain framework | identity and encryption trust |
| PoE | Power over Ethernet | data plus power over one cable |
| RPO | Acceptable data-loss window | how much loss is tolerable |
| RTO | Target restore window | how fast service must return |
| SLAAC | IPv6 self-addressing from router advertisements | IPv6 host self-configuration |
| SPAN | Port mirroring for inspection | send copies for packet analysis |
| SSID | Wireless network name | what clients select |
| STP | Loop-prevention method for switched networks | blocks redundant loop paths |
| TDR | Cable-fault location method | where the copper problem sits |
| VPC | Logically isolated cloud network | cloud networking boundary |
| VLAN | Logical Layer 2 segment | broadcast and access boundary |
| VXLAN | Overlay network for larger-scale segmentation | stretch segment logic over IP fabric |
| Pair | Keep this distinction clear |
|---|---|
| DNS vs DHCP | names versus addressing leases |
| NAT vs PAT | general translation versus many hosts sharing one public IP via ports |
| IDS vs IPS | observe and alert versus sit inline and block |
| RTO vs RPO | restore time versus acceptable loss window |
| MTBF vs MTTR | failure frequency versus recovery speed |
| STP vs LACP | prevent switching loops versus bundle links for throughput and resilience |
| VLAN vs subnet | Layer 2 boundary versus Layer 3 IP network boundary |
| in-band vs out-of-band management | production-path administration versus separate admin path when production is impaired |
| TACACS+ vs RADIUS | device-admin AAA bias versus broader network-access AAA fit |
| zero trust vs perimeter trust | verify continuously versus trust based mainly on location |
| If you keep mixing up… | Use this anchor |
|---|---|
| switch, router, and firewall | switch forwards inside a Layer 2 segment, router chooses Layer 3 path, firewall enforces policy |
| DNS, DHCP, and IPAM | DNS names things, DHCP leases addresses, IPAM inventories and governs addressing |
| latency, jitter, and packet loss | delay, delay variation, and missing packets |
| MFA, NAC, and segmentation | identity proof, admission control, and traffic separation |
| backup, snapshot, and baseline | recovery copy, point-in-time image, and approved intended state |
| multicast, broadcast, and anycast | subscribed group delivery, all-host segment delivery, and nearest-of-many destination |
DNS before blaming routing.PAT, not just generic NAT.STP; if the concern is combined links, think LACP.NAC; if the concern is “what can traffic reach after joining,” think segmentation or policy.RTO; if the concern is “how much loss,” think RPO.| If the term is really about… | Revisit this chapter |
|---|---|
| layers, media, protocols, topology, or addressing | 1. Concepts |
| routing, switching, wireless deployment, or installation choices | 2. Implementation |
| documentation, change, monitoring, backup, or remote management | 3. Operations |
| controls, segmentation, threats, hardening, or identity | 4. Security |
| symptoms, tools, and fault isolation | 5. Troubleshooting |
If a term keeps costing you points, jump back to the relevant lesson page instead of rereading this glossary repeatedly.