CCNA & Network+ Foundations

Comprehensive vocabulary flashcards covering network history, classifications, transmission modes, layered models, protocols, addressing, and modern networking paradigms.

ARPAnet

The Advanced Research Project Agency Network, initiated by the US Department of Defense in 1962, which served as the predecessor to the modern Internet and the TCP/IP suite.

Packet switching

A communication method where messages are routed or rerouted in multiple directions, ensuring network resilience even if critical nodes are destroyed.

LAN (Local Area Network)

A high-speed, privately owned network limited to a single site like an office or building, offering high scalability within that distance.

MAN (Metropolitan Area Network)

An extension of LANs across a city used for efficient regional resource sharing between local sites.

WAN (Wide Area Network)

A network with global reach provided by network providers, characterized by slower speeds than LANs and complex scalability.

Peer-to-Peer Model

An authentication model where all nodes are equals with no dedicated servers, leading to low scalability as node counts increase.

Server-Based Model

A model where dedicated, optimized servers control client access to provide high scalability and centralized management.

Simplex

A unidirectional transmission flow, such as a traditional broadcast.

Half-Duplex

Bidirectional communication that is not simultaneous, requiring coordination to prevent signal collisions.

Full-Duplex

Simultaneous bidirectional communication, serving as the enterprise standard for maximizing throughput.

Synchronous Transmission

A transmission mode where sender and receiver use the same time cycle, sending bits in a steady stream without start/stop bits.

Asynchronous Transmission

A mode where data is divided into packets with start/stop bits, allowing for varying delays or out-of-order arrival.

Service Interfaces

Local interfaces where a specific layer provides functions to the layer directly above it within the same system.

Syntax

An element of a protocol referring to the structure or format of the data, including the bit order.

Semantics

An element of a protocol referring to the meaning or interpretation of each section of bits.

Timing

An element of a protocol determining when data is sent and at what speed to prevent receiver saturation.

Access Networks

The infrastructure that connects end-systems or subscribers to the first router, categorized as residential, institutional, or mobile.

Core Networks

The main backbone connecting all routers and Internet Service Providers (ISPs) using high-speed packet and circuit switching.

Star Topology

An enterprise standard layout where nodes connect to a central hub or switch, ensuring a single cable failure does not collapse the entire segment.

Switch

A Data Link layer device that learns physical (MAC) addresses and delivers data only to the specific port of the destination device.

Subnetting Formula for Valid Hosts

$2^n - 2$, where $n$ represents the number of host bits remaining after the mask.

Magic Number (Block Size)

A calculation used in subnetting determined by $256 - \text{Interesting Octet}$, identifying the increments for subnets.

IPv6

A 128-bit addressing scheme providing an inexhaustible address space and more efficient header structure than IPv4.

OSPF (Open Shortest Path First)

The standard interior gateway protocol used for routing within an enterprise campus.

BGP (Border Gateway Protocol)

The exterior gateway protocol of the Internet that manages routing between different ISPs to ensure global scalability.

DNS (Domain Name System)

A service that resolves domain names to IP addresses and manages name disputes.

SLAAC (Stateless Address Autoconfiguration)

A method that allows IPv6 hosts to configure their own addresses without a central server.

ARP (Address Resolution Protocol)

A protocol used to resolve logical IP addresses to physical MAC addresses.

TCP (Transmission Control Protocol)

A connection-oriented transport protocol that uses a 3-Way Handshake ($SYN \rightarrow SYN-ACK \rightarrow ACK$) to ensure reliable application delivery.

UDP (User Datagram Protocol)

A connectionless transport protocol that prioritizes speed over reliability, commonly used for real-time applications like Voice and Video.

SDN (Software-Defined Networking)

An architecture that decouples the network's control plane (the brains) from its data plane (the forwarding engine).

NFV (Network Function Virtualization)

The practice of running network services such as firewalls and load balancers as software on commodity servers.

Infrastructure as Code (IaC)

The management of network state using automated scripts to reduce manual configuration errors.

Life Cycle Management

The planned replacement of aging hardware to maintain a stable and professional global infrastructure.