Cisco glossary
Key Cisco certification terms and acronyms.
Definitions are AI-assisted and reviewed for general accuracy — verify critical details against Cisco's official documentation.
802.1Q
An IEEE standard that inserts a 4-byte tag into Ethernet frames to identify VLAN membership across trunk links.
802.1X
An IEEE standard for port-based network access control that authenticates devices and users before granting access to the network.
ACLAccess Control List
An ordered set of permit or deny rules applied to a router interface to filter traffic based on IP addresses, protocols, or ports.
Ansible
An agentless IT automation tool that uses SSH or APIs with YAML playbooks to configure systems and network devices.
APIApplication Programming Interface
A defined interface that allows software components to communicate by exposing functions, data, or services to external consumers.
APIPAAutomatic Private IP Addressing
A feature on Windows hosts that self-assigns an address in the 169.254.0.0/16 range when a DHCP server cannot be reached.
ARPAddress Resolution Protocol
A Layer 2/3 protocol that resolves a known IPv4 address to its corresponding MAC address within the same broadcast domain.
BGPBorder Gateway Protocol
A path-vector EGP used to exchange routing information between autonomous systems on the internet and in enterprise networks.
CDPCisco Discovery Protocol
A Cisco-proprietary Layer 2 protocol that advertises device type, IP address, and interface information to directly connected Cisco devices.
CI/CDContinuous Integration / Continuous Delivery
A set of practices and toolchain stages that automate building, testing, and deploying software changes frequently and reliably.
CIDRClassless Inter-Domain Routing
An IP addressing method that replaces classful addressing by expressing network prefixes with variable-length subnet masks in slash notation.
default route
A static route with destination 0.0.0.0/0 that matches any packet for which no more specific route exists in the routing table.
DHCPDynamic Host Configuration Protocol
An application-layer protocol that automatically assigns IP addresses, subnet masks, gateways, and other parameters to network clients.
DMVPNDynamic Multipoint VPN
A Cisco WAN solution that allows dynamic creation of IPsec tunnels between spokes using mGRE and NHRP without hub configuration changes.
DNA CenterDigital Network Architecture Center
Cisco's network management and automation platform that provides REST APIs for intent-based networking operations such as device inventory and provisioning.
DNA CenterDigital Network Architecture Center
Cisco's centralized network management and automation platform used to design, provision, and assure enterprise networks.
DNSDomain Name System
A hierarchical naming system that resolves human-readable hostnames to IP addresses using UDP/TCP port 53.
Docker
An open platform for developing, shipping, and running applications inside isolated containers that package code and dependencies together.
DSCPDifferentiated Services Code Point
A 6-bit field in the IP header used to classify and mark packets for differentiated forwarding treatment in a QoS policy.
EIGRPEnhanced Interior Gateway Routing Protocol
A Cisco advanced distance-vector routing protocol that uses DUAL algorithm to provide fast convergence and loop-free paths.
EIGRPEnhanced Interior Gateway Routing Protocol
A Cisco advanced distance-vector routing protocol using DUAL algorithm to provide rapid convergence and loop-free paths.
FHRPFirst Hop Redundancy Protocol
A class of protocols (HSRP, VRRP, GLBP) that provide default gateway redundancy by sharing a virtual IP address among multiple routers.
Git
A distributed version control system that tracks changes to source files and enables collaboration through branching and merging.
gRPCGoogle Remote Procedure Call
A high-performance, open-source RPC framework using HTTP/2 and Protocol Buffers, used in model-driven telemetry on Cisco IOS XR and NX-OS.
HSRPHot Standby Router Protocol
A Cisco proprietary FHRP that provides gateway redundancy by electing an active and standby router sharing a virtual IP and MAC address.
HSRPHot Standby Router Protocol
A Cisco-proprietary first-hop redundancy protocol that assigns a virtual IP and MAC address shared by an active and standby router.
HTTPHypertext Transfer Protocol
An application-layer protocol defining methods (GET, POST, PUT, DELETE, PATCH) used for communication between clients and web servers including REST APIs.
IaCInfrastructure as Code
The practice of managing and provisioning infrastructure through machine-readable definition files rather than manual processes.
IPsecInternet Protocol Security
A suite of protocols that provides authentication, integrity, and encryption for IP communications at the network layer.
ISEIdentity Services Engine
A Cisco policy-based network access control platform that provides authentication, authorization, and posture assessment for endpoints.
JSONJavaScript Object Notation
A lightweight, human-readable data-interchange format using key-value pairs and arrays, commonly used in REST API payloads.
Kubernetes
An open-source container orchestration system that automates deployment, scaling, and management of containerized applications across clusters.
LISPLocator/ID Separation Protocol
A routing architecture that separates device identity (EID) from its location (RLOC) to improve routing scalability and mobility.
LLDPLink Layer Discovery Protocol
An IEEE 802.1AB vendor-neutral Layer 2 protocol that advertises device capabilities and connectivity information to directly connected neighbors.
Microservices
An architectural approach where an application is built as a collection of small, independently deployable services each responsible for a specific function.
MPLSMultiprotocol Label Switching
A forwarding mechanism that routes packets using short fixed-length labels rather than long IP addresses, enabling traffic engineering and VPNs.
NATNetwork Address Translation
A mechanism that translates private IP addresses to a public IP address, allowing multiple internal hosts to share a single routable address.
NETCONFNetwork Configuration Protocol
An IETF protocol (RFC 6241) that provides mechanisms to install, manipulate, and delete configurations of network devices over a secure session.
NETCONFNetwork Configuration Protocol
An IETF protocol (RFC 6241) that provides mechanisms to install, manipulate, and delete the configuration of network devices using XML and YANG.
NTPNetwork Time Protocol
An application-layer protocol that synchronizes clocks of network devices to a reference time source using UDP port 123.
NX-OSNexus Operating System
Cisco's modular network operating system for Nexus data center switches, which exposes NX-API and supports model-driven programmability.
OAuthOpen Authorization
An open standard (RFC 6749) for token-based delegated authorization, allowing third-party applications to access resources without exposing credentials.
OSPFOpen Shortest Path First
A link-state IGP that uses Dijkstra's SPF algorithm to calculate the shortest path to each destination within an autonomous system.
OSPFOpen Shortest Path First
A link-state interior gateway routing protocol that uses Dijkstra's algorithm to calculate the shortest path to each destination.
PIMProtocol Independent Multicast
A multicast routing protocol that uses existing unicast routing tables to build multicast distribution trees in sparse or dense mode.
PoEPower over Ethernet
A standard (IEEE 802.3af/at) that allows network switches to deliver electrical power to connected devices over standard Ethernet cabling.
Postman
A GUI-based API development and testing tool that allows users to build, send, and inspect HTTP requests and responses interactively.
PyatsPython Automated Test Systems
Cisco's open-source Python-based test automation framework for network validation, supporting structured parsing via the Genie library.
QoSQuality of Service
A set of techniques to manage network traffic by prioritizing certain data types to meet performance requirements for delay-sensitive applications.
QoSQuality of Service
A set of techniques used to manage network traffic by prioritizing certain data types to ensure performance for latency-sensitive applications.
RBACRole-Based Access Control
A security model that restricts system access by assigning permissions to roles, which are then assigned to users, limiting exposure to resources.
RESTRepresentational State Transfer
An architectural style for distributed hypermedia systems using stateless HTTP methods to interact with resources identified by URIs.
RESTCONF
An HTTP-based protocol defined in RFC 8040 that provides a REST API interface to YANG-modeled network device configuration and state data.
RESTCONFREST Configuration Protocol
An HTTP-based protocol (RFC 8040) that exposes YANG-modeled data using REST operations over a standardized URI structure.
RSTPRapid Spanning Tree Protocol
An IEEE 802.1w enhancement to STP that provides faster convergence through port roles and states such as discarding, learning, and forwarding.
SD-WANSoftware-Defined Wide Area Network
An architecture that uses software-defined networking to manage and optimize WAN connectivity across multiple transport links.
SDKSoftware Development Kit
A collection of tools, libraries, documentation, and sample code that accelerates development of applications targeting a specific platform or API.
SNMPSimple Network Management Protocol
An application-layer protocol used to monitor and manage network devices by polling MIB variables or receiving trap notifications.
SSHSecure Shell
A cryptographic network protocol that provides encrypted remote command-line access to network devices over TCP port 22.
StackWise
A Cisco technology that interconnects multiple physical switches into a single logical switch using a dedicated stacking cable and backplane.
STPSpanning Tree Protocol
A Layer 2 protocol defined in IEEE 802.1D that prevents switching loops by placing redundant ports in a blocking state.
STPSpanning Tree Protocol
A Layer 2 protocol defined in IEEE 802.1D that prevents switching loops by electing a root bridge and blocking redundant paths.
syslog
A standard protocol for forwarding log and event messages from network devices to a centralized syslog server using UDP port 514.
trunk
A switch port configured to carry traffic for multiple VLANs simultaneously, typically using IEEE 802.1Q encapsulation.
VLANVirtual Local Area Network
A logical segmentation of a switched network that groups ports or devices into separate broadcast domains regardless of physical location.
VLSMVariable Length Subnet Masking
A subnetting technique that allows different subnet masks to be applied within the same major network to use IP address space efficiently.
VRFVirtual Routing and Forwarding
A technology that creates multiple independent routing tables on a single router, allowing network path isolation without separate hardware.
VSSVirtual Switching System
A Cisco technology that combines two physical Catalyst switches into a single logical switch to simplify topology and eliminate STP blocked ports.
VXLANVirtual Extensible LAN
An encapsulation protocol defined in RFC 7348 that extends Layer 2 networks over a Layer 3 infrastructure using a 24-bit VNI.
Webhook
An HTTP callback mechanism where a server sends an HTTP POST to a registered URL when a specific event occurs, enabling event-driven integrations.
WPA2Wi-Fi Protected Access 2
An IEEE 802.11i-based wireless security standard that uses AES-CCMP encryption to protect wireless network communications.
XMLExtensible Markup Language
A markup language that encodes documents in a format both human-readable and machine-readable, used in NETCONF and some REST APIs.
YAMLYAML Ain't Markup Language
A human-readable data serialization standard often used for configuration files and automation playbooks such as Ansible.
YANGYet Another Next Generation
A data modeling language (RFC 6020/7950) used to model configuration and state data for network devices managed by NETCONF or RESTCONF.
YANGYet Another Next Generation
A data modeling language defined in RFC 7950 used to model configuration and state data for network devices managed via NETCONF or RESTCONF.