Computer Networking: Weeks 1, 4, 6, OSI, and TCP/IP

Comprehensive vocabulary flashcards covering foundational networking concepts, OSI and TCP/IP models, physical media, signaling, data link protocols, IP routing, transport protocols, and application layer services.

Network

Two or more devices connected so they can communicate and share resources.

Networking

The process of connecting and managing devices so they can communicate.

Node

Any device or connection point on a network.

Host

A device that communicates on a network.

Endpoint

A device at the edge of a network, such as a computer, phone, or server.

Client

A device or application that requests a service.

Server

A system that provides a service or resource to other systems.

LAN (Local Area Network)

A network covering a relatively small geographic area, such as a home, lab, or office building.

WAN (Wide Area Network)

A network connecting networks across larger geographic areas.

WLAN (Wireless LAN)

A local network in which devices communicate using radio waves instead of cables.

Internet

A global network of interconnected IP networks.

ISP (Internet Service Provider)

A company or organization that provides Internet connectivity.

Protocol

A defined set of agreed-upon rules devices use when communicating.

Protocol Stack

A group of networking protocols working together at different layers.

Payload

The actual data being carried inside a packet, frame, segment, or other PDU.

Header

Information added to data by a networking protocol to control delivery and processing.

Bandwidth / Link Capacity

The rated or theoretical maximum data capacity a link can carry; in signal theory, the frequency range measured in Hz.

Throughput

The actual rate of data successfully delivered over a connection under real conditions.

Latency

The amount of delay or time a transmission takes to reach its destination.

Topology

The physical or logical arrangement of devices on a network.

Star Topology

A cabling layout where all devices connect independently through a central device.

Bus Topology

A topology where all devices share a common communication medium.

Ring Topology

A loop structure where each node connects to neighbors.

Mesh Topology

A topology providing multiple connections and paths between devices for redundancy.

Redundancy

Having backup components or communication paths available if something fails.

Single Point of Failure

A single component whose failure can disrupt an entire system or service.

Connectivity

The ability of devices to communicate with one another.

Configuration

The settings that determine how a device or network operates.

Troubleshooting

The systematic process of identifying, diagnosing, and correcting network problems.

Ping

A basic network diagnostic utility used to test whether another host can be reached.

OSI Model

Open Systems Interconnection Model — a seven-layer conceptual framework used to understand and troubleshoot network communication.

Layer

A logical level of the OSI model responsible for particular networking functions.

Encapsulation

The process of adding networking information (headers/trailers) as data moves down through the networking layers.

De-encapsulation

The process of removing networking information as received data moves back up through the layers.

PDU (Protocol Data Unit)

The specific name given to a data unit at a particular networking layer.

Application Data

Information created or used by an application before transport across the network.

Segment

A common term for a TCP Protocol Data Unit at Layer 4.

Datagram

A term commonly associated with a UDP Protocol Data Unit at Layer 4.

Packet

The Layer 3 Protocol Data Unit used for logical network transmission.

Frame

The Layer 2 Protocol Data Unit that organizes bits and includes MAC addresses.

Bit

A binary digit with a value of 0 or 1; the basic unit of Layer 1 transmission.

Byte

A group of eight bits; capitalized 'B' represents bytes, lowercase 'b' represents bits.

Application Layer (OSI Layer 7)

Provides user-facing network services used by applications.

Presentation Layer (OSI Layer 6)

Handles data representation, formatting, encoding, encryption, and compression.

Session Layer (OSI Layer 5)

Establishes, manages, and terminates communication sessions between applications.

Transport Layer (OSI Layer 4)

Provides end-to-end communication, port addressing, and flow control between applications.

Network Layer (OSI Layer 3)

Handles logical addressing and routing of packets between different networks.

Data Link Layer (OSI Layer 2)

Handles communication across the local network link using MAC addresses.

Physical Layer (OSI Layer 1)

Transmits and receives raw bits as physical signals across a transmission medium.

TCP/IP Model

A four-layer networking model describing how protocols work together across IP networks and the Internet.

TCP/IP Protocol Suite

The collection of protocols that power IP networks and modern Internet communication.

Network Access Layer (TCP/IP)

TCP/IP layer responsible for local link communication and physical transmission; maps to OSI Layers 1 and 2.

Internet Layer (TCP/IP)

TCP/IP layer responsible for logical addressing and packet routing; maps to OSI Layer 3.

Transport Layer (TCP/IP)

TCP/IP layer responsible for end-to-end communication between applications; maps to OSI Layer 4.

Application Layer (TCP/IP)

TCP/IP layer providing services to applications; combines OSI Layers 5, 6, and 7.

Transmission Medium

The physical material or pathway that carries a signal, such as copper, glass fiber, or air.

Signal

A measurable physical change used to represent information, such as changing voltage, light pulses, or RF waves.

Encoding / Line Coding

Rules for representing digital data as a pattern of physical signal levels or transitions.

Modulation

The process of varying a carrier signal's properties (amplitude, frequency, or phase) to represent information.

Symbol

One transmitted signal state during a defined time interval; a symbol can represent multiple bits.

Baud / Symbol Rate

The number of symbols transmitted per second; can differ from bits per second.

Bit Rate

The number of bits transmitted each second, measured in bps, Mbps, or Gbps.

Carrier

A continuous wave whose properties are modified during modulation to carry data.

Baseband

Signaling in its original frequency range without shifting it onto a higher-frequency carrier wave.

Amplitude

The height, size, or physical strength of a signal wave (e.g., voltage level).

Frequency

The number of repeating wave cycles that occur each second, measured in hertz (Hz).

Hertz (Hz)

The standard unit of frequency equal to one cycle per second.

GHz (Gigahertz)

One billion hertz; the standard frequency scale for Wi-Fi bands (2.4, 5, and 6 GHz).

Period

The time required for a wave to complete one full cycle.

Wavelength

The physical distance covered by one complete wave cycle from peak to peak.

Phase

The position of a periodic wave within its cycle relative to a reference point.

Attenuation

The loss of signal strength or power as a signal travels through a medium or over distance.

Noise / EMI

Unwanted disturbances from electrical or electromagnetic sources that disrupt signals.

Crosstalk

Unwanted coupling or bleeding of electrical signal energy from one wire pair into another.

SNR (Signal-to-Noise Ratio)

The ratio comparing desired signal power to background noise power; higher SNR indicates a cleaner link.

BER (Bit Error Rate)

The fraction or percentage of received bits that contain errors.

Duplex

The direction pattern of communication across a network link.

Half-Duplex

A transmission mode where connected devices must take turns sending and receiving.

Full-Duplex

A transmission mode allowing simultaneous bidirectional transmission and reception without collisions.

Auto-Negotiation

A process where Ethernet link partners exchange capabilities to select the highest shared speed and duplex mode.

Link Status

The state of whether a local physical Layer 1 connection is established.

Transceiver

A hardware module or component that combines both a transmitter and a receiver.

Repeater

A Layer 1 device that regenerates and amplifies an incoming signal to overcome attenuation and extend distance.

Hub

A Layer 1 multiport repeater that repeats incoming bits out of all other connected ports.

Media Converter

A hardware device that converts signals between different physical media, such as copper to fiber optic.

PoE (Power over Ethernet)

A technology that delivers electrical power and network data simultaneously over copper Ethernet cabling.

PAM (Pulse-Amplitude Modulation)

A modulation method using pulse amplitude levels; PAM4 uses four distinct voltage levels.

QAM (Quadrature Amplitude Modulation)

A modulation technique that varies both carrier amplitude and phase to carry data.

OFDM

Orthogonal Frequency-Division Multiplexing — a wireless signaling method splitting data across many subcarriers.

Copper Cabling

Electrical wiring used to transmit data as changing voltage pulses.

Twisted-Pair Cable

Copper Ethernet cabling with insulated wire pairs twisted together to reduce EMI and crosstalk.

UTP (Unshielded Twisted Pair)

Twisted-pair copper cable without extra metallic shielding.

STP (Shielded Twisted Pair)

Twisted-pair copper cable with conductive shielding to protect against severe EMI.

Cat5e

Enhanced Category 5 twisted-pair cable supporting Gigabit Ethernet up to 100 meters.

Cat6

Category 6 twisted-pair cable with tighter twists and less crosstalk than Cat5e.

Cat6a

Augmented Category 6 twisted-pair cable designed for 10 Gigabit Ethernet up to 100 meters.

8P8C / RJ45

The eight-position, eight-contact modular connector standard used on copper Ethernet patch cables.

T568A / T568B

Two wiring color standards defining pair termination order inside an 8P8C/RJ45 connector.

Auto-MDIX

An automated port feature that detects cable pinouts and internally flips transmit and receive pairs as needed.

Straight-Through Cable

An Ethernet cable wired identically on both ends; connects unlike devices (PC to switch).