Introduction to Networks Flashcards
What is the Internet?
A huge network of computers and devices all over the world, connected through wires and signals, that share information using routers and links
What is not the Internet?
Web pages belong to the World Wide Web, which runs on top of the Internet.
WiFi is just one way to connect to the Internet, not the Internet itself
Define computer network and internet (lowercase ‘i’).
Computer network: A group of connected computers that share data and resources.
internet (small i): A collection of connected networks making a bigger network
Define the global Internet (capital ‘I’).
The worldwide system of all connected networks (internets), made up of devices, cables, routers, and switches that move data everywhere
What is networking?
Sending messages from one device to another over a network, using switches to decide the path
What are the main types of switching schemes?
Broadcast: Send to everyone.
Circuit switching: Set up a fixed path before talking.
Packet switching: Break message into pieces, send each one its own way.
Which switching scheme does the Internet use?
Packet switching
What are the three main parts of the Internet’s structure?
Network Edge: The users (like phones, laptops, servers)
Access Network: The connection (like Wi-Fi, cables)
Network Core: The middlemen (routers/switches that move data)
What are access ISPs?
ISPs are the companies that connect people to the Internet. They can be:
Home ISPs (like broadband at your house)
School/Work ISPs (used in institutions)
Mobile ISPs (like 4G/5G on phones)
What is the role of the network core?
Route and forward packets, it moves data from one router to another until it reaches the final destination.
What is an IXP?
Internet Exchange Point - ISPs connect to exchange data directly, improving speed and reducing costs
Define a distributed system.
Multiple computers work together by sending messages to each other, but there’s no single clock and parts of it might fail
What is an intranet?
Private network within an organization, where access rules and firewalls control who can connect and what can be accessed
What is a firewall?
Security system that filters network traffic using rules to protect an intranet from external threats
Define speed, bandwidth, and throughput.
Speed: How fast data travels.
Bandwidth: Maximum data that can be transmitted per unit of time.
Throughput: Actual data successfully transmitted per unit of time.
What is link delay?
Time to send one packet across a single link (e.g., Delay=RL)
Where L=packet length, R=link bandwidth
What causes queueing and packet loss?
If packets come in too fast, they wait in a buffer. If the buffer gets full, extra packets are lost
What is end-to-end delay?
Time it takes for a packet to go from source to destination, including delays for sending, traveling, waiting in queues, and processing
What is a protocol?
Set of rules that determine how systems in a network communicate, including how messages are formatted and the order in which they are sent
Name some key Internet protocols and their uses.
HTTP/HTTPS: Used for browsing websites (Web).
SMTP/POP3: Used for sending/receiving emails (Email).
TCP/UDP: Manage how data is sent between computers (Transport).
IP: Routes data to the correct destination (Routing).
Ethernet: Handles the physical transfer of data over networks (Physical).
What is protocol layering?
A hierarchy where each layer has a specific task and communicates with the layers above and below it
What is the Internet Protocol Suite (TCP/IP stack)?
A 5-layer stack:
* Application
* Transport
* Network
* Link
* Physical
What is encapsulation?
Each layer adds its own header to the data before sending it to the next layer
What’s a key trade-off of protocol layering?
Pros: Easy to manage and fix because each layer has its own job.
Cons: Extra layer info slows things down a bit.
