Term 421
Open Systems Interconnection
The Open Systems Interconnection (OSI) model is a conceptual framework used to understand how data travels from one computer to another across a network.
Acronym study
Terms 421–450 of 716 CCNA acronyms and key terms. Each entry includes a plain-English definition and a link to the full 800-word glossary page with exam context and practice questions.
Term 421
The Open Systems Interconnection (OSI) model is a conceptual framework used to understand how data travels from one computer to another across a network.
Term 422
An Optical Network Terminal (ONT) is a device that connects your home or office to the internet service provider's fiber optic network, converting light signals into electrical signals your devices can use.
Term 423
Origin access control is a security mechanism that restricts access to a network, system, or resource based on the verified identity or attributes of the requesting entity.
Term 424
The OSI model is a conceptual framework that standardizes the functions of a telecommunication or computing system into seven distinct layers, from physical hardware to application software.
Term 425
OSPF is a link-state routing protocol that uses the SPF algorithm to compute the shortest path to each destination within a single autonomous system.
Term 426
OSPF is a link-state routing protocol used to find the best path for data packets to travel across IP networks, like a smart GPS that recalculates routes when traffic changes.
Term 427
An OSPF adjacency is a logical neighbor relationship formed between two OSPF routers that have completed a series of hello and database exchange processes, enabling them to share routing information and maintain a consistent view of the network topology.
Term 428
An OSPF area is a logical grouping of routers and networks within an OSPF routing domain, used to control routing traffic and improve scalability.
Term 429
OSPF authentication is a security mechanism that verifies the identity of routers exchanging routing information within an OSPF network, preventing unauthorized or malicious routing updates.
Term 430
OSPF cost is a metric used by the Open Shortest Path First routing protocol to determine the best path for data packets to travel through a network, based on the characteristics of each link.
Term 431
OSPF metric is a cost value assigned to each route in an Open Shortest Path First network, used to determine the best path for data packets.
Term 432
An OSPF neighbor is another router that has been directly discovered through OSPF Hello packets and is willing to exchange routing information to build a network topology map.
Term 433
OSPF network type defines how the Open Shortest Path First routing protocol operates on a given interface, determining neighbor discovery, adjacency formation, and the election of designated routers.
Term 434
OSPFv2 is a network routing protocol that helps routers share information about the best paths to send data across an IP network.
Term 435
OSPFv3 is the version of the Open Shortest Path First routing protocol that supports IPv6 networks, enabling routers to exchange routing information for IPv6 addresses.
Term 436
Out-of-band refers to a separate, dedicated network path used for managing and configuring IT devices, distinct from the main data traffic path.
Term 437
An Outbound ACL is a set of rules applied to traffic leaving a network interface that decides which packets are allowed to exit and which are blocked.
Term 438
An Outside global address is the publicly routable IP address assigned to a device on the external network (usually the internet) as seen from the perspective of a network device performing Network Address Translation (NAT).
Term 439
Outside local is the IP address that a device on the inside of a private network appears to have from the perspective of hosts located outside the network, typically after Network Address Translation (NAT) has been applied.
Term 440
A packet is a small unit of data that is sent over a network, containing both the actual data and control information for delivery.
Term 441
Packet capture is the process of intercepting and recording data packets traveling over a computer network for analysis.
Term 442
Packet loss is the failure of one or more data packets to reach their destination across a network, resulting in missing or incomplete data transfers.
Term 443
Port Aggregation Protocol (PAgP) is a Cisco proprietary protocol that automatically bundles multiple physical Ethernet links into a single logical link to increase bandwidth and provide redundancy.
Term 444
A Personal Area Network is a small network used for connecting devices close to one person, usually within a range of about 10 meters.
Term 445
Partner Interconnect is a Google Cloud service that allows you to connect your on-premises network to Google Cloud through a supported third-party service provider.
Term 446
A passive interface is a network interface that participates in a routing protocol (like OSPF) by listening for and learning routes, but does not send routing protocol messages out of that interface.
Term 447
PAT (Port Address Translation) is a method of network address translation that maps multiple private IP addresses to a single public IP address by using different port numbers for each connection.
Term 448
A short, flexible cable used to connect electronic devices to each other or to a network, often temporarily or for testing.
Term 449
Path cost is a numerical value assigned to each network path used by the Spanning Tree Protocol to determine the most efficient route and prevent loops in a switched network.
Term 450
A PDU (Protocol Data Unit) is the unit of data at a specific layer of the OSI or TCP/IP model, containing both header and payload information as it travels across a network.