Acronyms are useful only when the letters lead somewhere. Open Shortest Path First (OSPF) should lead to a routing relationship and learned routes. Link Aggregation Control Protocol (LACP) should lead to a logical bundle and member state. Received Signal Strength Indicator (RSSI) and signal-to-noise ratio (SNR) should lead to different wireless measurements. Use this page when the initials interrupt your study, then return to the guide or command output and apply the term in context.
This reference covers 65 acronyms and terms used in the published CCNA v2.0 guides and supporting resources. The stable CCNA address keeps the lookup in one place instead of splitting terminology across exam-version folders.
Context still matters. DR means Designated Router in the OSPF material on this page, while the same initials can mean something else in another field. AP usually means access point in CCNA networking. Read the surrounding scenario before treating an expansion as the answer.
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Search by acronym, full expansion, practical meaning, related term, or CCNA v2.0 domain.
Showing all 65 entries.
A
- AAA
- Authentication, Authorization, and Accounting A framework that verifies identity, decides permitted actions, and records activity.
- ACL
- Access Control List A set of rules that permits or denies access to a resource, network path, or object.
- AES
- Advanced Encryption Standard A symmetric encryption standard used by modern Wi-Fi security and many other security protocols.
- AI
- Artificial Intelligence Computer systems that perform tasks such as analysis, recommendation, generation, or decision support; CCNA v2.0 includes AI-assisted network operations.
- AP
- Access Point A wireless infrastructure device that connects Wi-Fi clients to the network.
- API
- Application Programming Interface A defined way for software components or services to exchange requests and data.
- ARP
- Address Resolution Protocol A protocol that maps an IPv4 address to a local network hardware address.
B
- BDR
- Backup Designated Router The backup to the designated router on an OSPF broadcast network segment.
- BOOTP
- Bootstrap Protocol An older address-configuration protocol whose relay behavior is related to DHCP relay on IOS.
- BPDU
- Bridge Protocol Data Unit A spanning-tree control frame used by switches to exchange topology information.
C
- CDP
- Cisco Discovery Protocol A Cisco discovery protocol that advertises neighboring device identity and interface information on the local link.
- CIDR
- Classless Inter-Domain Routing Prefix-length notation and route aggregation that describe networks without relying on legacy address classes.
- CLI
- Command-line Interface A text-based interface used to enter commands and inspect device or operating-system output.
- CPU
- Central Processing Unit The processor that executes instructions. High utilization can affect control-plane work, services, or device responsiveness.
- CRC
- Cyclic Redundancy Check An error-detection calculation used to identify corrupted frame data; increasing CRC errors can point to a physical-link problem.
D
- DAI
- Dynamic ARP Inspection A Layer 2 security feature that validates ARP messages against trusted information such as DHCP snooping bindings.
- DHCP
- Dynamic Host Configuration Protocol A protocol that automatically assigns IP configuration to network clients.
- DNS
- Domain Name System The distributed service that maps names to records such as IP addresses and mail servers.
- DR
- Designated Router The OSPF router elected on a multiaccess segment to reduce adjacency and flooding complexity.
E
- EUI-64
- Extended Unique Identifier, 64-bit A 64-bit identifier format; modified EUI-64 can derive an IPv6 interface identifier from a 48-bit MAC address.
F
- FHRP
- First Hop Redundancy Protocol A category of protocols that provide a resilient virtual default gateway for hosts.
H
- HSRP
- Hot Standby Router Protocol A Cisco first-hop redundancy protocol that provides a virtual default gateway using Active and Standby roles.
I
- ICMP
- Internet Control Message Protocol A network protocol used for diagnostics and control messages, including many ping and error responses.
- IoT
- Internet of Things A broad category of connected sensors, appliances, controllers, and embedded devices that communicate over a network.
- IP
- Internet Protocol The network-layer protocol used to address and route packets between systems.
- IPsec
- Internet Protocol Security A suite of protocols that protects IP traffic and is commonly used to build encrypted VPNs.
L
- LACP
- Link Aggregation Control Protocol The standards-based protocol used to negotiate and maintain compatible links inside an Ethernet link-aggregation group.
- LAN
- Local Area Network A network covering a limited area such as an office, home, or campus segment.
- LLDP
- Link Layer Discovery Protocol A vendor-neutral local-link discovery protocol that advertises device, interface, VLAN, power, and other neighbor information.
M
- MAC
- Media Access Control The data-link layer function and hardware addressing used on local networks.
- MDI-X
- Medium-Dependent Interface Crossover An Ethernet interface wiring role; auto-MDI-X can automatically adapt transmit and receive pair usage.
- MTU
- Maximum Transmission Unit The largest network-layer packet or link-layer payload an interface can carry without fragmentation or another accommodation.
N
- NAT
- Network Address Translation A network function that rewrites IP address information between address spaces.
- NIC
- Network Interface Card The hardware or virtual adapter that connects a system to a network and supplies link-layer functions such as a MAC address.
O
- OSPF
- Open Shortest Path First A link-state interior routing protocol that calculates shortest paths from exchanged topology information and uses areas for scale.
P
- PAT
- Port Address Translation A form of NAT that maps many internal connections to one public address by tracking transport-layer ports.
- PoE
- Power over Ethernet Supplies electrical power and Ethernet data over compatible copper cabling to devices such as access points, phones, and cameras.
- PVST+
- Per-VLAN Spanning Tree Plus Cisco spanning-tree behavior that maintains a separate spanning-tree instance for each VLAN; Rapid PVST+ uses rapid convergence behavior.
R
- RADIUS
- Remote Authentication Dial-In User Service A protocol that centralizes authentication, authorization, and accounting for network access.
- RF
- Radio Frequency Electromagnetic radio energy used by wireless networks; channel selection, interference, signal level, and noise affect performance.
- RFC
- Request for Comments A document in the Internet standards and technical publication series; RFC numbers are commonly used to identify protocol specifications and addressing guidance.
- RSSI
- Received Signal Strength Indicator A measurement of received wireless signal level.
S
- SAE
- Simultaneous Authentication of Equals The password-authentication exchange used by WPA3-Personal.
- SCP
- Secure Copy Protocol A secure file-copy protocol that uses SSH to protect transfers.
- SFTP
- SSH File Transfer Protocol A secure file-transfer protocol carried over SSH and used for protected transfer of files such as configurations and images.
- SNMP
- Simple Network Management Protocol A protocol used to monitor and manage network devices and report operational information.
- SNR
- Signal-to-Noise Ratio The difference between useful signal level and background noise; higher SNR generally provides a cleaner wireless signal.
- SSH
- Secure Shell A protocol for encrypted remote administration, command execution, tunneling, and file transfer.
- SSID
- Service Set Identifier The human-readable wireless network name advertised or configured for a Wi-Fi service.
- STP
- Spanning Tree Protocol A Layer 2 loop-prevention protocol that selects a root bridge and blocks redundant paths until they are needed.
- SVI
- Switch Virtual Interface A logical Layer 3 interface associated with a VLAN on a switch.
T
- TACACS+
- Terminal Access Controller Access-Control System Plus A protocol commonly used for centralized administration access to network devices, with separate authentication, authorization, and accounting functions.
- TCP
- Transmission Control Protocol A connection-oriented transport protocol that provides ordered delivery, acknowledgments, retransmission, and flow control.
- TKIP
- Temporal Key Integrity Protocol A legacy Wi-Fi encryption mechanism associated with older WPA deployments and weaker than modern AES-based protection.
U
- UDP
- User Datagram Protocol A connectionless transport protocol with low overhead and no built-in delivery guarantee.
V
- VLAN
- Virtual Local Area Network A logical Layer 2 network segment created on switching infrastructure.
- VLSM
- Variable Length Subnet Masking Using different prefix lengths within an address plan so subnets can be sized for different requirements.
- VM
- Virtual Machine A software-defined computer that runs a guest operating system with virtualized processor, memory, storage, and network interfaces.
- VoIP
- Voice over Internet Protocol Voice communication carried over IP networks, often using switch features such as voice VLANs and Power over Ethernet for attached phones.
- VPN
- Virtual Private Network An encrypted tunnel that protects traffic across an untrusted network.
- VRRP
- Virtual Router Redundancy Protocol A standards-based first-hop redundancy protocol that provides a virtual gateway using Master and Backup roles.
W
- WEP
- Wired Equivalent Privacy An obsolete wireless security protocol with serious weaknesses; recognize it as an insecure legacy choice.
- WLAN
- Wireless Local Area Network A local network that uses Wi-Fi radio links instead of only wired Ethernet connections.
- WPA2
- Wi-Fi Protected Access 2 A widely deployed Wi-Fi security generation commonly paired with AES-based protection.
- WPA3
- Wi-Fi Protected Access 3 A newer Wi-Fi security generation that strengthens authentication and encryption compared with older personal-network designs.
No matching terms were found. Try the full phrase, a neighboring protocol, or a broader networking concept.
Use the expansion to recover the job
The full phrase often tells you what to inspect next. Hot Standby Router Protocol (HSRP) and Virtual Router Redundancy Protocol (VRRP) both point toward first-hop gateway redundancy. Cisco Discovery Protocol (CDP) and Link Layer Discovery Protocol (LLDP) point toward directly connected neighbor evidence. Dynamic Host Configuration Protocol (DHCP) should make you think about the client, relay, server, pool, and return path rather than only the server.
Similar initials are easier to keep apart when you attach them to evidence. Received Signal Strength Indicator (RSSI) describes received wireless signal level, while signal-to-noise ratio (SNR) compares useful signal with noise. Administrative distance is not an acronym you need to force into memory as AD; the useful distinction is that it compares route sources, while a routing protocol metric compares paths within that protocol.
Official reference
Use the official Cisco 200-301 CCNA v2.0 exam topics as the final scope checklist for exams beginning February 3, 2027. Cisco documentation is also the authoritative source when product terminology or command behavior varies by platform or software release.