Network - Networking Fundamentals Flashcards
Computer Network
A computer network is a group of connected devices that can communicate with each other.
📌 Example: The WiFi in your home is a small computer network where devices like laptops and phones are connected.
Network Topology
Network topology is how devices (computers, routers, switches) are connected in a network.
🔹 Types of Network Topologies:
1️⃣ Bus – All devices share one cable (like a public bus route 🚌).
2️⃣ Star – All devices connect to a central hub (like spokes on a wheel 🌟).
3️⃣ Ring – Devices form a circle and pass data around 🔄.
4️⃣ Mesh – Every device connects to multiple devices (like a spider web 🕸️).
5️⃣ Hybrid – A mix of two or more topologies 🔀.
🔹 Example:
Home WiFi uses a star topology (all devices connect to the router).
The Internet is mostly a mesh topology (many connections for reliability).
🔹 Analogy:
Network topology is like a city’s road system—how streets, highways, and intersections connect everything! 🚗🛣️
The Network Edge
The network edge includes the devices at the ends of a network, like computers, phones, and servers.
📌 Example: A smartphone connected to the internet is a device at the network edge.
Hosts (End Systems)
Hosts are devices connected to a network that send and receive data.
📌 Example: A laptop and a web server are both network hosts.
Access Networks
Access networks connect users to the internet, either wired (Ethernet, DSL) or wireless (WiFi, 4G/5G).
📌 Example: Your home router connects your devices to the internet via an access network.
The Network Core
The network core is the main part of the internet that moves data super fast between different networks.
🔹 What does it do?
✅ Sends data quickly between cities & countries.
✅ Uses high-speed cables & routers to keep the internet running.
🔹 Example:
When you watch a YouTube video, the data travels through the network core from YouTube’s servers to your device.
🔹 Analogy:
The network core is like a highway for internet traffic 🚗💨—data moves fast without stopping at every small road.
Packet Switching
Data is broken into small pieces (packets) and sent across the network, where routers decide the best path.
📌 Example: When you send an email, it is split into packets and reassembled at the destination.
Circuit Switching
A dedicated communication path is set up before sending data, and no other data can use that path.
📌 Example: Old telephone networks used circuit switching, where a full connection was set up before a call.
Forwarding vs. Routing
Forwarding moves packets inside a router to the correct output.
Routing finds the best path to send packets to the destination.
📌 Example: A router at home forwards data between devices, while an ISP router finds the best path to another country.
Network Protocols
Protocols are rules that decide how computers communicate in a network.
📌 Example: HTTP is a protocol that defines how web browsers request websites.
OSI Model (7 Layers)
A conceptual model that describes how data moves through a network.
📌 Example: When you send a message on WhatsApp, it goes through multiple layers, including the transport layer (TCP) and network layer (IP).
Layers of OSI Model:
1️⃣ Physical Layer – Sends raw bits through cables or airwaves.
📌 Example: A WiFi signal or Ethernet cable is part of this layer.
2️⃣ Data Link Layer – Manages direct connections between devices.
📌 Example: Your network adapter (MAC address) ensures data goes to the right device.
3️⃣ Network Layer – Finds the best path for data using IP addresses.
📌 Example: Routers use IP addresses to send packets between networks.
4️⃣ Transport Layer – Ensures data is delivered correctly (TCP/UDP).
📌 Example: TCP resends lost packets, ensuring complete delivery.
5️⃣ Session Layer – Manages communication sessions between applications.
📌 Example: Video calls stay connected using session management.
6️⃣ Presentation Layer – Formats data (encryption, compression).
📌 Example: HTTPS encrypts web traffic using TLS.
7️⃣ Application Layer – User-level interactions (browsers, email).
📌 Example: Web browsers use HTTP/HTTPS to load websites.
The Internet Protocol (IP)
IP assigns addresses to devices and helps route packets.
📌 Example: Your phone gets an IP address when it connects to WiFi.
Transmission Control Protocol (TCP)
TCP ensures data is delivered completely and correctly.
📌 Example: Downloading a file uses TCP, so no part is missing.
User Datagram Protocol (UDP)
UDP sends data faster but does not check for errors.
📌 Example: Live video streaming uses UDP to avoid delays.
Encapsulation
Each network layer adds extra information (headers) to a message before sending it.
📌 Example: When you send an email, multiple layers wrap it in extra data to help it travel through the network.
Bandwidth
Bandwidth is how much data can be sent or received over a network per second. It’s like the size of a highway—the wider it is, the more cars (data) can travel at the same time.
🔹 Measured in:
Mbps (Megabits per second)
Gbps (Gigabits per second)
🔹 Example:
A high-bandwidth internet (1 Gbps) = Faster downloads & smoother streaming. 🚀
A low-bandwidth internet (10 Mbps) = Slow loading & buffering. 🐌
Latency (Delay)
🔹 What is latency?
Latency is the delay in data travel—how long it takes for data to go from one place to another and back.
🔹 Measured in:
Milliseconds (ms)
🔹 Example:
Low latency (10ms) → Fast response (good for gaming 🎮, video calls 📹).
Latency is how long it takes for data to travel across a network.
📌 Example: High latency causes lag in online games.
Packet Loss
When a network drops packets due to congestion or errors.
📌 Example: Bad WiFi signals cause video buffering because packets are lost.
Throughput
Throughput is the actual speed of data transfer, which may be lower than bandwidth.
📌 Example: A WiFi router advertises 100 Mbps, but actual throughput might be 50 Mbps due to interference.
Throughput helps us measure how fast data actually moves in a network. We use it to:
🔹 Check internet speed – To see if your connection is fast enough for streaming, gaming, or video calls. 📶🎮📺
🔹 Optimize networks – Companies use throughput to improve performance and avoid slow connections. 🚀
🔹 Troubleshoot problems – If a network is slow, checking throughput helps find issues like congestion or weak signals. 🛠️
🔹 Compare network performance – Helps decide which internet provider or network setup is better. 📊
In short: Throughput helps see how fast data moves and fix slow networks! ⚡
(IXP)
Internet Exchange Point
A physical location where ISPs connect to exchange traffic.
📌 Example: Google and Facebook use IXPs to serve data faster to users.
Domain Name System (DNS)
DNS translates website names into IP addresses.
📌 Example: When you type “google.com”, DNS finds its IP address (e.g., 8.8.8.8).
HTTP & HTTPS
HTTP (HyperText Transfer Protocol) loads web pages.
HTTPS (secure version) encrypts traffic.
📌 Example: Online banking uses HTTPS for security.
Ethernet
Ethernet is a wired networking standard that connects devices using cables.
📌 Example: Offices use Ethernet for faster and stable internet connections.
WiFi (802.11)
🔹 What is WiFi?
WiFi is a wireless technology that lets devices connect to the internet without cables.
🔹 How does it work?
1️⃣ Your WiFi router gets internet from your ISP (via cable or fiber).
2️⃣ The router sends the internet as radio signals 📡.
3️⃣ Your phone, laptop, and TV receive the signals and connect to the internet.
🔹 Example:
When you use your phone to browse the internet at home, it’s connected to WiFi, not mobile data.
🔹 Analogy:
WiFi is like a speaker 📢—it sends internet signals through the air, and nearby devices can “hear” and connect.
✅ Faster than mobile data, but needs to stay close to the router! 🚀WiFi is a wireless standard that connects devices to a network.
📌 Example: Your phone connects to WiFi instead of using mobile data.
