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A comprehensive set of vocabulary flashcards covering fundamental concepts, components, transmission modes, network types, topologies, media, protocols, OSI/TCP-IP models, addressing, and common network applications from the lecture notes.
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Data communications
Exchange of data between two devices via a transmission medium using hardware and software in a communication system.
Computer Network
A system of interconnected computers and devices that share resources using a communication channel
Intermediary Devices vs End devices
End devices are source or destination of data in a network while Intermediary connect end devices
Data Flow
Simplex - Data moves inly one way
Half duplex - Data moves both ways but one at a time
Duplex - Data moves both ways simultaneously
Elements that a pritocol controls
Encoding
Formatting
Timing
Size
Delivery options
Media
Refers to means used to transmit data between devices in a network.
Wavelength
Distance a simple signal travels during one period; λ = c / f; related to propagation in media.
Guided media
Also wired media. Transmission media that guide signals along a physical path (twisted-pair, coax, fiber, ethetnet, fiber optic, USB cable).
Unguided media
Wireless transmission through air/space without a physical conductor. Uses electromagnetic waves like radio, Infrared, Microwaves, Satellite
Twisted-pair
Two copper conductors twisted to reduce interference; used in telephony and LANs.
Repeater
Physical-layer device that regenerates signals to extend the distance of a network.
Network Topologies
Physical or logical arrangement of network components
Bus, Star, Ring, Mesh, Tree, Hybrid
Network connecting devices
Hub – Connects multiple devices and broadcasts data to all,
Switch – Connects devices and sends data only to the intended device,
Router – Connects different networks and directs data between them,
Bridge – Connects and filters traffic between two network segments,
Gateway – Connects networks using different protocols,
Access Point – Provides wireless connectivity to devices,
Modem – Converts digital signals to analog and vice versa for internet access
Network security threats
Trojans – Malicious programs disguised as legitimate software that give attackers access to your system,
Worms – Self-replicating malware that spreads across networks without user intervention,
Ransomware – Malware that encrypts files and demands payment to restore access,
Spam – Unsolicited messages, often emails, used to advertise, scam, or deliver malware
Modulation techniques
Analogue- Amplitude Modulation (AM), Frequency Modulation (FM), Phase Modulation (PM),
Digital - Amplitude Shift Keying (ASK), Frequency Shift Keying (FSK), Phase Shift Keying (PSK)
Encoding
Process of converting data into a specific format for efficient transmission, storage, or security e.g ASII
Security Measures
Firewall, Antivirus, Encryption, Access Control, Intrusion Detection System (IDS), Strong Passwords, Updates/Patching
Coaxial Bus
network topology where all devices are connected to a single coaxial cable (the bus) that carries data in both directions.
Pros: Simple to install, uses less cable than star topology.
Cons: A break in the main cable stops the entire network, performance decreases with more devices.
Peer-to-Peer (P2P) Workgroup
a type of network where all computers have equal status and can share resources (files, printers) directly without a central server.
Pros: Easy to set up, low cost, suitable for small networks.
Cons: Harder to manage as the network grows, less secure than server-based networks.
Conglomeration
refers to the combination of several different companies or entities into a single larger organization, often operating in diverse industries.
Client-Server Paradigm
a network model where clients (users’ devices) request services from a central server, which processes and provides the requested resources or data.
Pros: Centralized management, better security, and easier maintenance.
Cons: Server failure can disrupt the entire network; can be expensive to set up.
Wireless Communication
is the transfer of information between devices without physical cables, using electromagnetic waves such as radio, microwave, or infrared.
Physical Networks
refer to the actual hardware and layout of a network, including cables, devices, and connection points that enable communication.
Examples of physical network types:
LAN (Local Area Network) – Network confined to a small area like an office or building.
WAN (Wide Area Network) – Covers large geographical areas, e.g., the internet.
MAN (Metropolitan Area Network) – Spans a city or large campus.
PAN (Personal Area Network) – Small network for personal devices, e.g., Bluetooth connections.
Logical Network
Logical Network refers to the virtual or conceptual arrangement of devices and data flow in a network, regardless of the physical connections. It defines how data moves and how devices communicate.
Examples:
IP addressing schemes – Defines how devices are identified on the network.
VLANs (Virtual LANs) – Groups devices logically even if they are physically apart.
Subnets – Divides a network into smaller, manageable segments.
Open Systems Interconnection (OSI) Reference Model
is a conceptual framework that standardizes how different network systems communicate in seven layers.
Seven layers of OSI
Application Layer → Presentation Layer –> Session Layer –> Transport Layer –> Network Layer –> Data Link Layer → Physical Layer
Error division strategies
are techniques used in networks to identify and fix errors that occur during data transmission.
Common strategies:
Parity Check – Adds a parity bit (even or odd) to detect single-bit errors.
Checksum – Sums data values and sends the result; receiver checks for consistency.
Cyclic Redundancy Check (CRC) – Uses polynomial division to detect errors in data blocks.
Hamming Code – Adds redundant bits to detect and correct single-bit errors.
Automatic Repeat Request (ARQ) – Requests retransmission when errors are detected.
Logical vs Physical topologies
Logical Topology – Shows how data flows in a network, regardless of physical connections, e.g., token passing in a ring network.
Physical Topology – Shows the actual layout of cables and devices in a network, e.g., star or bus layout.
Key Difference: Logical focuses on data movement, physical focuses on device connections.
Types of Casting
Types of Casting – Methods of delivering data to devices in a network:
Unicast – Data sent from one sender to one specific receiver.
Broadcast – Data sent from one sender to all devices in the network.
Multicast – Data sent from one sender to a specific group of devices.
Anycast – Data sent from one sender to the nearest or best receiver in a group.
Protocols
are rules and standards that govern how data is transmitted and received over a network. They ensure devices can communicate effectively.
Common network protocols:
HTTP/HTTPS – For web browsing and secure web communication.
FTP – For transferring files between devices.
SMTP – For sending emails.
IMAP/POP3 – For receiving emails.
TCP – Ensures reliable data transmission.
UDP – Sends data quickly without guaranteed delivery.
IP – Addresses and routes packets across networks.
DNS – Converts domain names into IP addresses.
Multiplexing
combine multiple signals or data streams over a single communication channel to optimize resource use.
Common types of multiplexing:
Frequency Division Multiplexing (FDM) – Different signals use different frequency bands.
Time Division Multiplexing (TDM) – Signals take turns using the channel in time slots.
Wavelength Division Multiplexing (WDM) – Used in fiber optics; signals use different light wavelengths.
Code Division Multiplexing (CDM) – Signals are encoded with unique codes to share the same channel.
Bandwidth
is the maximum amount of data that can be transmitted over a network channel in a given time, usually measured in bits per second (bps).
Higher bandwidth → More data can be sent quickly.
Lower bandwidth → Slower data transmission.