CCNA Automation key terms

A data modeling language that describes the structure and constraints of configuration and state data, so tools can read and change device settings in a consistent, vendor-neutral way.

A network management protocol that runs over SSH, encodes messages in XML, and uses YANG-modeled operations such as get-config and edit-config to read and change device configuration.

A protocol that exposes YANG-modeled data through HTTP methods such as GET, POST, PUT, PATCH, and DELETE, returning JSON or XML and mapping closely to CRUD-style automation.

A property of an operation that produces the same end state whether it runs once or many times, which lets automation safely retry without duplicating configuration or creating conflicting objects.

An approach where the operator describes the intended end state and the tool works out the commands needed to reach it, contrasting with step-by-step imperative command lists.

Managing devices and services through version-controlled definition files rather than manual CLI changes, so builds are repeatable, reviewable, and recoverable from a known source of truth.

The gradual divergence between a device's running configuration and the intended baseline, often caused by manual changes, which automation detects and corrects by re-applying the source of truth.

A YAML file that lists ordered tasks applied to inventory hosts, usually over SSH without an agent, using modules that are largely idempotent and reusable across many devices.

A reusable package of code, such as Netmiko, NAPALM, or requests, that a script imports to handle SSH sessions, API calls, or data parsing instead of writing low-level protocol code.

An HTTP interface where resources are addressed by URLs, actions map to standard methods, and responses are typically JSON, making it easy for scripts to read and change state.

A lightweight text format of objects, arrays, strings, numbers, booleans, and null that is widely used for API payloads and is directly parseable by most programming languages.

A three-digit number in an API response indicating outcome, such as 200 for success, 201 for created, 400 for a bad request, 401 for unauthorized, and 404 for not found.

A credential string issued after login and sent with later API requests, often in an Authorization header, so the client need not resend a username and password each time.

A design where a central software controller provisions, monitors, and applies policy to many devices through southbound interfaces, while operators and applications use northbound APIs.

The protocol and data model a controller uses to reach managed devices, such as NETCONF, RESTCONF, SNMP, or CLI, carrying the intent down to the network elements.

The interface a controller exposes upward to scripts, orchestration tools, and applications, letting them request services or read state without knowing device-level command syntax.

A structured, agreed representation of objects and their relationships, such as interfaces and addresses, that lets tools exchange configuration and state without parsing free-form CLI text.

A working copy of configuration that can be edited, validated, and then committed as a single transaction, allowing changes to be prepared and rolled back before taking effect.

Software-defined networking separates the control plane that decides forwarding from the data plane that moves packets, enabling centralized programmatic policy and automated provisioning.

A software-defined approach to wide-area connectivity that centrally manages multiple WAN links, applies application-aware policy, and steers traffic based on path quality.

A logical topology built by tunneling packets across an underlying physical network, commonly used in fabrics and SD-WAN to decouple service addressing from transport addressing.

A tunneling protocol that encapsulates Layer 2 frames inside UDP and uses a 24-bit VNI, allowing far more isolated segments to stretch across a routed Layer 3 underlay.

An interconnected set of switches and links managed as one system, often with a controller, providing resilient any-to-any forwarding for hosts and services across the topology.

The functions that build the forwarding information a device uses, including routing protocol exchanges, topology calculation, and neighbor adjacencies, separate from actual packet movement.

The forwarding path that matches incoming packets against tables and moves them out an interface, also called the forwarding plane, where per-packet work is done.

A device's list of known destinations with next hops, outgoing interfaces, and metrics, from which the best path for each prefix is selected and installed for forwarding.

A value ranking the trustworthiness of a route source on a Cisco device, where lower is preferred, so a static route usually wins over the same prefix learned by OSPF.

The rule that a router forwards a packet using the most specific matching route, so a /28 entry is chosen over a /24 entry that also contains the destination address.

A manually configured path to a destination via a next hop or exit interface, which does not adapt automatically and is often used for small networks or default paths.

A route for the all-zeros prefix that matches any destination not covered by a more specific entry, commonly used to send unknown traffic toward an upstream provider.

A Layer 2 broadcast domain created logically on switches, letting one physical infrastructure carry separate segments that are isolated from each other unless routed.

A switch interface that carries traffic for multiple VLANs, tagging frames so the receiving device can tell which broadcast domain each frame belongs to.

A switch interface assigned to a single VLAN that connects to an end device, sending and receiving untagged frames because the VLAN is implied by the port configuration.

The standard that inserts a four-byte tag into an Ethernet frame, carrying a 12-bit VLAN identifier so trunk links can multiplex many VLANs over one physical connection.

The VLAN whose frames travel untagged on an 802.1Q trunk; both ends must agree on it, otherwise traffic is misplaced or leaked between mismatched segments.

A switch's record of which MAC addresses were seen on which ports, used to forward frames only out the correct interface instead of flooding them everywhere.

A protocol that automatically supplies hosts with an IP address, mask, default gateway, and DNS servers through a lease process of discover, offer, request, and acknowledgment.

A hierarchical naming system that resolves human-readable names to IP addresses, which clients query so applications can reach services without hard-coded addresses.

A protocol that synchronizes device clocks to a reference time source, keeping timestamps consistent so logs, certificates, and scheduled automation behave predictably.

A standard for sending event messages to a local buffer or remote collector, using severity levels from emergency down to debug to help with troubleshooting and auditing.

A management protocol where an agent on a device exposes structured variables in a MIB that a manager can poll or receive in traps for monitoring and alerting.

A translation technique that rewrites source or destination addresses, most often letting many private hosts share one public address through port address translation.

A set of mechanisms that classify, mark, queue, and schedule traffic so latency-sensitive or business-critical flows get preferential treatment when links are congested.

An ordered list of permit and deny rules matched against packet fields, used to filter traffic, restrict management access, or identify flows for other features.

The framework for authentication, authorization, and accounting, often using a central server such as RADIUS or TACACS+, so access is verified, limited, and logged.

An encrypted protocol for remote command-line access and file transfer that replaces cleartext Telnet, protecting credentials and session data from eavesdropping on the network.

A switch feature that limits which or how many MAC addresses may appear on an interface, taking action such as shutdown when an unauthorized device connects.

A switch safeguard that marks ports facing clients as untrusted, so only trusted ports may send DHCP offers and rogue servers cannot hand out false addressing information.

A link-state interior gateway protocol that floods link information within an area, builds a shared topology database, and runs shortest-path calculation to choose routes.

A 32-bit value that separates the network and host portions of an IPv4 address, determining which addresses are local and which must be reached through a router.

A shorthand that writes an address followed by a slash and the count of leading network bits, such as /24, making prefix length and address range easy to express.

The router address a host sends packets to when the destination is outside its local subnet, serving as the exit point toward other networks.

The 128-bit addressing scheme that replaces IPv4, using hexadecimal groups and offering a vastly larger address space plus built-in neighbor discovery and stateless autoconfiguration.

A connection-oriented transport protocol that performs a handshake, numbers segments, acknowledges delivery, and retransmits lost data to provide reliable ordered streams.

A connectionless transport protocol that sends datagrams without handshakes or delivery guarantees, favored for low-overhead traffic such as voice, DNS queries, and VXLAN.

A 16-bit identifier that selects the application or service on a host, letting one IP address support many simultaneous conversations distinguished by port pairs.

The saved configuration a device loads at boot, held in nonvolatile storage, which differs from the running configuration until changes are explicitly saved.