Topic 9: Fundamentals of Communication & Networking

Baud rate

The number of signal changes in the communication medium per second[cite: 62].

Bit rate

The number of bits transmitted over the communication medium per second[cite: 62].

Bandwidth

The range of frequencies that a communication medium is capable of transmitting[cite: 62].

Latency

The difference in time between an action being initiated and its effect being noticed[cite: 62].

Protocol

A set of rules relating to communication between devices[cite: 62].

Serial data transmission

Data is sent one bit at a time over a single communication line[cite: 63].

Parallel data transmission

Uses numerous parallel communication lines to send multiple bits simultaneously[cite: 63].

Skew

A problem in parallel transmission where bits sent together are received at slightly different times due to varying electrical properties[cite: 63].

Crosstalk

An issue in parallel transmission where signals from tightly packed lines leak into one another and corrupt data[cite: 64].

Synchronous data transmission

A shared clock signal is used by both sender and receiver to time when signals are sent[cite: 64].

Asynchronous data transmission

Uses start and stop bits to indicate transmission duration without needing a shared clock signal[cite: 64].

Physical star topology

A network layout where each client has its own direct connection to a central hub[cite: 67].

Physical bus topology

A network layout where clients connect to a single shared cable backbone terminated at both ends[cite: 68].

Client-server network

A setup where one or more central servers provide services and management to network clients[cite: 69].

Peer-to-peer network

A setup where services are provided directly by clients with equal status, eliminating the need for a central server[cite: 69].

WiFi

A wireless local area network based on international standards enabling seamless connectivity[cite: 70].

CSMA/CA

A wireless protocol where devices listen to check if a communication channel is idle before transmitting to avoid collisions[cite: 71].

RTS/CTS

A wireless protocol adding request-to-send and clear-to-send messages to handle hidden nodes[cite: 71].

Packet

A container used to transmit data across networks, containing sender and recipient addresses, payload contents, and TTL[cite: 74, 75].

Router

A network device that reads packet recipient addresses to forward data via the fastest route[cite: 75].

Gateway

A device connecting networks with different protocols by stripping old protocol details and reassigning addresses for the new protocol[cite: 75].

Fully Qualified Domain Name (FQDN)

A domain name specifying an exact resource that can be interpreted in only one way, always including the host name[cite: 76].

Domain Name Server (DNS)

A system that translates human-friendly domain names into their corresponding IP addresses using lookup tables[cite: 77].

Internet registry

An organisation responsible for allocating IP addresses and protecting depleting unallocated pools[cite: 77].

Packet filtering

A firewall mechanism that accepts or blocks packets based on source IP addresses or port/protocol numbers[cite: 78].

Stateful inspection

A firewall mechanism that examines packet contents and tracks active network connections before allowing traffic[cite: 78].

Proxy server

A server sitting between public and private networks that manages packets and masks internal private IP addresses for anonymity[cite: 78].

Symmetric encryption

Encryption where both sender and receiver share the same private key to both encrypt and decrypt data[cite: 79].

Asymmetric encryption

Encryption using a mathematically related key pair—a public key for encryption and a private key for decryption[cite: 79].

Digital signature

An encrypted message digest using the sender's private key appended to verify sender identity and ensure data integrity[cite: 80].

Digital certificate

A file issued by a certificate authority that verifies the ownership of an asymmetric key pair[cite: 81].

Worm

Malware that can self-replicate between computers across a network or via downloaded malicious files[cite: 82].

Trojan

Malware disguised as a benign file that users are tricked into opening[cite: 82].

Virus

Malware requiring an executable host file to reside in, lying dormant until the host file runs[cite: 82].

TCP/IP Stack

A communication protocol architecture formed from four distinct layers: application, transport, network, and link[cite: 86].

Application Layer (TCP/IP)

Selects and uses the correct protocol to transmit data, interacting directly with the user via application software like web browsers[cite: 86].

Transport Layer (TCP/IP)

Establishes an end-to-end virtual path, splits data into packets, and assigns port and sequence numbers[cite: 86].

Network Layer (TCP/IP)

Provides the correct source and destination IP addresses for each packet, where routers operate[cite: 86, 87].

Link Layer (TCP/IP)

Controls physical network connections and appends unique MAC addresses to packets, which change with every network hop[cite: 87].

Socket Address

A combination of an IP address and a port number separated by a colon that identifies a specific application on a device[cite: 87].

FTP (File Transfer Protocol)

A protocol running on ports 20 & 21 used for transferring files between devices via anonymous or non-anonymous access[cite: 88].

SSH (Secure Shell)

A protocol running on port 22 used for secure remote management, computer access, and command execution with encryption[cite: 88].

HTTP (Hypertext Transfer Protocol)

A protocol running on port 80 used by web servers to deliver unencrypted text web pages to clients[cite: 88].

HTTPS (Hypertext Transfer Protocol Secure)

A protocol running on port 443 that performs the same function as HTTP but encrypts data during transmission for security[cite: 88].

POP3 (Post Office Protocol 3)

A protocol running on ports 110 & 995 used to check for and download new emails from an email server[cite: 88].

SMTP (Simple Mail Transfer Protocol)

A protocol running on ports 25, 587 & 465 used for sending emails between a client and an email server[cite: 88].

Subnet Mask

A bitmask used alongside an IP address with a bitwise AND operation to determine the network identifier and subnet[cite: 89].

IPv4 Address

A 32-bit address consisting of four dotted quad bytes representing numbers from 0 to 255, providing roughly 4 billion unique addresses[cite: 90].

IPv6 Address

A 128-bit address formed of eight blocks of four hexadecimal characters separated by colons, providing around 10^37 unique addresses[cite: 90].

Routable vs Non-Routable IP Addresses

Routable (public) IP addresses are globally unique, whereas non-routable (private) IP addresses can be reused across different isolated private networks[cite: 90].

DHCP (Dynamic Host Configuration Protocol)

A system that dynamically assigns temporary private IP addresses to devices from a shared pool as they join a network[cite: 91].

NAT (Network Address Translation)

A technique where a router replaces a device's private IP address with its own public IP address for internet communication, recording the mapping to handle responses[cite: 91].

Port Forwarding

A mechanism used when a client needs to access a server on a private network by sending packets to the router's public IP and port, which are then forwarded via NAT[cite: 92].

WebSocket Protocol

An application-layer API providing a constant, full-duplex stream of data between two devices with reduced packet headers[cite: 92].

REST (Representational State Transfer)

A design methodology for online database applications that maps HTTP methods (POST, GET, PUT, DELETE) to database CRUD operations[cite: 93].

CRUD Operations

An acronym representing the four basic database functions: Create (INSERT), Retrieve (SELECT), Update (UPDATE), and Delete (DELETE)[cite: 93].

JSON vs XML

JSON is a data format that is more compact, easier to read, easier to create, and faster for computers to process than XML[cite: 94].

Thin-Client Network

A network where the majority of processing power and storage belongs to central servers, keeping clients inexpensive and easily managed centrally[cite: 95].

Thick-Client Network

A network where independent clients possess their own processing power and storage, eliminating the need for a central server[cite: 95].