Networks

What is a computer network?

Two or more computers connected to share resources and data

Why use computer networks?

Share files, share hardware, communication, centralized management

What is a standalone computer?

Computer not connected to a network

What is a LAN?

Local Area Network (covers small geographical area)

Examples of where LANs are used?

Homes, schools, offices, single buildings

Who owns/maintains a LAN?

The organization using it

What is a WAN?

Wide Area Network (covers large geographical area)

Example of a WAN?

The Internet

Who owns/maintains a WAN?

Multiple organizations, telecom companies

Key difference between LAN and WAN?

Geographical size and ownership

What connects LANs together to form WAN?

Routers and telecommunications infrastructure

What is network topology?

The layout/arrangement of devices in a network

What is a star topology?

All devices connect to central switch/hub

Advantages of star topology?

If one cable fails, only that device affected; easy to add devices; fast performance

Disadvantages of star topology?

If central switch fails, whole network down; requires lots of cabling; expensive

What is a bus topology?

All devices connected to single main cable (backbone)

Advantages of bus topology?

Cheap, uses less cable, easy to add devices

Disadvantages of bus topology?

If main cable fails, whole network fails; performance degrades with more devices; difficult to identify faults

What is a mesh topology?

Each device connected to multiple other devices

Types of mesh topology?

Full mesh (all connected to all) and partial mesh (some connected to some)

Advantages of mesh topology?

Very reliable (multiple paths); data can reroute if path fails; no single point of failure

Disadvantages of mesh topology?

Expensive (lots of cables/wireless connections); complex to set up and maintain

Where are mesh topologies commonly used?

Internet backbone, critical systems requiring high reliability

What is wired networking?

Connecting devices using physical cables

What is wireless networking?

Connecting devices using radio waves (Wi-Fi)

What is Ethernet?

Wired networking standard using cables

Types of Ethernet cable?

Twisted pair (Cat5e, Cat6), fiber optic

What is twisted pair cable?

Cable with pairs of copper wires twisted together

Advantages of twisted pair cable?

Cheap, flexible, easy to install

Disadvantages of twisted pair cable?

Limited distance (100m), susceptible to interference

What is fiber optic cable?

Cable using light pulses through glass/plastic fibers

Advantages of fiber optic cable?

Very fast, long distances, no electrical interference, secure

Disadvantages of fiber optic cable?

Expensive, fragile, difficult to install

What is Wi-Fi?

Wireless networking technology

Advantages of wireless networks?

No cables needed, devices can move freely, easy to connect new devices

Disadvantages of wireless networks?

Slower than wired, limited range, less secure, interference issues

What is a NIC?

Network Interface Card (hardware for connecting to network)

What is a wireless access point?

Device that allows wireless devices to connect to wired network

What is a switch?

Device connecting multiple devices in a LAN and directing data to correct recipient

What is a router?

Device connecting different networks together and directing traffic between them

What is a modem?

Device converting digital signals to analogue (and vice versa) for transmission over phone lines

What is a hub?

Basic device broadcasting data to all connected devices (outdated)

Difference between switch and hub?

Switch sends data only to intended recipient; hub sends to all

What is a server?

Powerful computer providing services/resources to other computers

Types of servers?

File server, web server, email server, database server

What is a client?

Computer accessing services from a server

What is a client-server network?

Network where central server provides resources to client computers

Advantages of client-server network?

Centralized management, better security, centralized backup, controlled access

Disadvantages of client-server network?

Expensive (server costs), server failure affects all clients, requires technical expertise

What is a peer-to-peer (P2P) network?

Network where all computers are equal and share resources

Advantages of P2P network?

Cheap (no server needed), easy to set up, no single point of failure

Disadvantages of P2P network?

Difficult to manage, less secure, no centralized backup, slower performance

When to use client-server?

Large organizations, need for security and centralized control

When to use peer-to-peer?

Small networks, home/small office, limited budget

What is network hardware?

Physical devices needed for networking

What is network performance measured by?

Bandwidth and latency

What is bandwidth?

Maximum amount of data that can be transmitted per second

What is bandwidth measured in?

Bits per second (bps), usually Mbps or Gbps

What is latency?

Time delay in data transmission

What affects network performance?

Bandwidth, number of users, type of connection, network traffic, interference

How does more users affect performance?

Reduces available bandwidth per user, increases congestion

What is a protocol?

Set of rules for data transmission and communication

Why are protocols needed?

Ensure different devices can communicate correctly

What is TCP/IP?

Transmission Control Protocol/Internet Protocol (main internet protocol suite)

What does TCP do?

Breaks data into packets, ensures reliable delivery, reassembles packets

What does IP do?

Addresses and routes packets across networks

What is a packet?

Small unit of data transmitted over network

What information is in a packet?

Header (addresses, sequence number) and payload (actual data)

Why break data into packets?

Efficient transmission, can take different routes, easier error checking

What is HTTP?

HyperText Transfer Protocol (for web pages)

What is HTTPS?

Secure HTTP (encrypted web communication)

What is FTP?

File Transfer Protocol (for uploading/downloading files)

What is SMTP?

Simple Mail Transfer Protocol (for sending emails)

What is POP3/IMAP?

Protocols for receiving emails

What is DNS?

Domain Name System (converts domain names to IP addresses)

Example of DNS in action?

Converting www.google.com to 172.217.169.46

What is an IP address?

Unique numerical address identifying a device on network

What is IPv4?

IP address version 4 (32-bit, e.g., 192.168.1.1)

What is IPv6?

IP address version 6 (128-bit, allows more addresses)

Why was IPv6 created?

IPv4 addresses running out

What is a MAC address?

Unique hardware address assigned to NIC

Can MAC address be changed?

Technically yes, but it's permanent in hardware

What is the Internet?

Global network of interconnected networks (WAN)

What is the World Wide Web (WWW)?

Collection of web pages accessed via Internet

Difference between Internet and WWW?

Internet is infrastructure; WWW is service running on it

What is a URL?

Uniform Resource Locator (web address)

Parts of a URL?

Protocol (http://), domain (www.example.com), path (/page.html)

What is a web browser?

Software for accessing and displaying web pages

Examples of web browsers?

Chrome, Firefox, Safari, Edge

What is a search engine?

Website that indexes and searches web content

Examples of search engines?

Google, Bing, DuckDuckGo

What is cloud storage?

Storing data on remote servers accessed via Internet

Examples of cloud storage?

Google Drive, Dropbox, OneDrive, iCloud

Advantages of cloud storage?

Access from anywhere, automatic backup, no local storage needed, easy sharing

Disadvantages of cloud storage?

Requires Internet connection, privacy concerns, ongoing costs, dependent on provider

What is cyber security?

Protecting computer systems from digital threats

Why is cyber security important?

Prevent data theft, protect privacy, maintain system functionality, avoid financial loss

What is a cyber threat?

Potential danger to computer systems/data

What is malware?

Malicious software designed to harm systems

Types of malware?

Virus, worm, trojan horse, spyware, adware, ransomware, rootkit