Network Systems and Design Master Revision Notes

Flashcards covering the fundamentals of network systems, including hardware, protocols, addressing, design, and troubleshooting as well as testing and troubleshooting procedures.

Computer Network

A collection of interconnected devices that exchange information and share resources using communication links and networking protocols.

Protocol

A set of rules that govern communication between devices.

Node

Any device connected to the network capable of sending or receiving data, such as a computer, laptop, smartphone, or router.

Link

The connection between devices, which can be wired or wireless; no communication is possible unless devices are connected by links.

Router

A device that connects different networks and functions at OSI Layer $3$ for routing and packet forwarding.

Switch

A device that connects devices inside one LAN and sends data only to the correct computer at OSI Layer $2$.

Server

A network component that provides services to clients, such as files, web pages, or email.

Client

A device or application that requests services from servers across a network.

NIC (Network Interface Card)

A hardware component that connects a device to the network.

Personal Area Network (PAN)

The smallest network type with a range of $1-10$ metres, typically used for Bluetooth or wireless keyboards.

Local Area Network (LAN)

A high-speed network covering one building, such as a school, office, or hospital.

Metropolitan Area Network (MAN)

A network that covers a city, like a county government network or an ISP.

Wide Area Network (WAN)

The largest network type that connects countries and continents, with the Internet as the primary example.

Network Topology

The physical or logical arrangement of devices in a network.

Star Topology

A configuration where every device connects to a central switch; it is fast and easy to troubleshoot but relies on the central switch.

Bus Topology

A setup where all devices share one cable; it is cheap but difficult to troubleshoot and sensitive to cable failure.

Mesh Topology

A highly redundant configuration where every device connects to every other device.

Hub

A Layer $1$ device with no intelligence that broadcasts data to every computer on the network.

Modem

A device that converts digital signals to analogue and vice versa to connect homes to ISPs.

Wireless Access Point

A device that provides $\text{Wi-Fi}$ connectivity to a network.

Fibre Optic Cable

High-speed transmission media immune to electromagnetic interference, capable of long-distance data transfer.

UTP (Unshielded Twisted Pair)

Cheap and easy-to-install cabling, though limited by distance and susceptible to electromagnetic interference.

OSI Model

A seven-layer reference model developed by ISO: Physical, Data Link, Network, Transport, Session, Presentation, and Application.

TCP (Transmission Control Protocol)

A reliable, connection-oriented protocol used by $\text{HTTP}$, $\text{HTTPS}$, and $\text{FTP}$.

UDP (User Datagram Protocol)

A fast, connectionless protocol without acknowledgements, used for video streaming, gaming, and $\text{VoIP}$.

Bandwidth

The maximum amount of data that can be transmitted per second.

Latency

The delay before data reaches its destination.

Throughput

The actual amount of data successfully transferred over a network.

MAC Address

A unique physical address assigned by the manufacturer to a network interface card at Layer $2$.

IP Address

A unique logical address assigned to a device on a network at Layer $3$.

Port Number

A $16-bit$ number ranging from $0$ to $65535$ that identifies a specific application running on a device.

Socket Address

A combination of an IP Address and a Port Number (e.g., $192.168.1.10:80$).

IPv4

A $32-bit$ addressing system written in decimal notation consisting of four octets range $0-255$ each.

IPv6

A $128-bit$ addressing system written in hexadecimal, developed to provide a huge number of addresses.

Private IP Address

Addresses used inside organizations for internal communication, such as Class C range $192.168.0.0 – 192.168.255.255$.

CIDR (Classless Inter-Domain Routing)

A method that replaced classful addressing to provide flexible subnet sizes and efficient address allocation.

Subnetting

The process of dividing one large network into smaller subnetworks to improve performance and security.

Physical Network Design

The process of planning hardware infrastructure like routers, switches, racks, and cooling systems.

Logical Network Design

Focuses on how data moves through the network, including IP addressing, routing, and VLANs.

Site Survey

The inspection of a location to gather info on building layout, user requirements, and interference before network installation.

Redundancy

Providing backup components like routers, switches, or power supplies to ensure continuous operation.

Network Testing

Checking whether a network is working correctly, efficiently, and securely according to design specifications.

Jitter

The measurement of variation in packet arrival times; high values cause poor video or voice quality.

Load Testing

Testing network performance under normal expected traffic conditions.

Stress Testing

Testing the network beyond its normal operating capacity to identify its breaking point.

Vulnerability Assessment

A security test that searches for weaknesses like weak passwords or unpatched software.

Penetration Testing

A security test that simulates cyber-attacks to determine if unauthorized access is possible.

Ping

A diagnostic tool used to test connectivity between two devices.

Traceroute (Tracert)

A command that shows the path and routers a packet passes through to reach its destination.

nslookup

A tool used to test DNS name resolution for translating domain names into IP addresses.

Preventive Maintenance

Regular activities like software updates and cable inspections performed to prevent network failures.

Virus

A malicious program that spreads between computers.

Worm

A type of self-replicating malware.

Trojan Horse

Malware that is disguised as legitimate software.

Phishing

A cyber threat that tricks users into revealing sensitive information.

DoS Attack

An attack that overloads a network or server to make it unavailable.