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Computer Networking > Intro Week 1 > Flashcards

Intro Week 1 Flashcards

(65 cards)

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1
Q

When to Break Up Networks?

A

> 250 devices in single subnet (broadcast overhead)
Different security requirements (student vs admin networks)
Different performance needs (research vs email)
Geographic separation (different buildings)

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2
Q

Wireless Data Transmission Steps?

A

📱 Your Phone → 📶 Radio Waves → 📡 Access Point Electrical signals(Ethernet) → Router → Light Pulses (Fiber) → ISP → More Fiber → YouTube ✅

Think of it like shouting in a room - everyone hears you, but only the intended person responds.

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3
Q

AP as Signal Translator?

A

Radio Waves ←→ Access Point ←→ Electrical Signals
(WiFi) │ (Ethernet)
│
Bridge Between
Wireless & Wired

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4
Q

What is a computer network?

A

Two or more devices connected together to share resources, exchange data, and communicate across distances.

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5
Q

What are the four core functions of computer networking?

A
  1. Resource Sharing 2. Communication 3. Data Exchange 4. Distributed Computing
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6
Q

What is the difference between physical and logical topology?

A

Physical topology = actual layout of cables and connections. Logical topology = how data flows through the network regardless of physical connections.

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7
Q

What is Bus Topology?

A

All devices connect to a single shared cable (backbone). Pros: Low cost, simple. Cons: Single point of failure, performance degrades with more devices.

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8
Q

What is Star Topology?

A

All devices connect to a central hub/switch. Pros: Fault isolation, easy management, dedicated bandwidth. Cons: Central device is single point of failure.

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9
Q

What is Ring Topology?

A

Devices connected in circular pattern, data travels in one direction. Pros: Fair access, no collisions (token passing). Cons: Single break stops entire network.

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10
Q

What is Mesh Topology?

A

Multiple connections between devices. Pros: Maximum redundancy, fault tolerance, load distribution. Cons: Expensive, complex configuration.

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11
Q

How many connections needed for full mesh with n devices?

A

n(n-1)/2 connections.

Example: 4 devices = 6 connections, 10 devices = 45 connections.

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12
Q

What is the Internet hierarchy (ISP structure)?

A

Tier 1 ISPs (global backbone) → Tier 2 ISPs (regional) → Tier 3 ISPs (local) → Your home router.

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13
Q

What topology do major ISPs use for backbone networks?

A

Partial Mesh topology - provides redundancy and multiple paths without the expense of full mesh.

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14
Q

Why do home networks use star topology?

A

Devices don’t need to communicate with each other, most traffic goes to internet, cost-effective for small number of devices.

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15
Q

What is the difference between wired backbone and internet backbone?

A

Wired backbone = Ethernet cables within a building. Internet backbone = Major fiber cables connecting cities/countries.

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16
Q

What is network isolation and why is it important?

A

Separating network segments to contain problems. Prevents broadcast storms from affecting entire network.

Example: faulty device flooding one subnet doesn’t crash whole campus.

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17
Q

When should networks be broken into subnets?

A

When >250 devices (broadcast overhead), different security needs, different performance requirements, or geographic separation.

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18
Q

What is the difference between a switch and a router?

A

Switch: Operates within ONE subnet, uses MAC addresses, Layer 2. Router: Connects DIFFERENT subnets, uses IP addresses, Layer 3.

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19
Q

What are private IP addresses and why are they used?

A

Non-routable addresses (192.168.x.x, 10.x.x.x) used internally. Allows address reuse, provides security, enables NAT to conserve public IPs.

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20
Q

What is NAT (Network Address Translation)?

A

Process where router changes private IP addresses to public IP addresses for internet communication. Uses port numbers to track multiple internal devices.

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21
Q

How does NAT handle multiple devices with same private IP?

A

Router creates unique port mappings.

Example: 192.168.1.10:5000 → Public IP:60001, 192.168.1.10:5001 → Public IP:60002.

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22
Q

What is the difference between local and internet communication?

A

Local: Same network, direct switch forwarding, no internet needed. Internet: Different networks, requires routing through internet infrastructure.

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23
Q

What does WiFi stand for?

A

WiFi doesn’t stand for anything - it’s a marketing brand name. Technical name is IEEE 802.11.

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24
Q

What is an Access Point (AP)?

A

Device that bridges wireless and wired networks. Converts radio signals to electrical signals and acts like a wireless switch for connected devices.

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25
How do switches learn device locations?
MAC address learning - switch records which port each MAC address is connected to by examining source addresses of incoming frames.
26
What happens when a switch doesn't know a destination MAC address?
Flooding - switch sends the frame to ALL ports except the source port, then learns from the response.
27
What is a broadcast storm?
When a faulty device sends excessive broadcast messages, overwhelming the network and preventing normal traffic from flowing.
28
What is the physical composition of the internet?
Undersea fiber cables (70% international traffic), terrestrial fiber networks, data centers, Internet Exchange Points (IXPs), cell towers.
29
How is data transmitted over different media?
Ethernet: Voltage changes (5V=1, 0V=0). Fiber: Light pulses (light=1, no light=0). WiFi: Radio frequency changes.
30
Why do enterprise networks use hybrid topologies?
Different network segments have different requirements. Core needs redundancy (mesh), distribution needs some redundancy (partial mesh), access needs cost efficiency (star).
31
What is partial mesh topology?
Selected redundant connections between devices - provides some fault tolerance and multiple paths without the full cost of complete mesh.
32
How do wireless mesh networks work?
Multiple access points or devices create redundant wireless paths. If one fails, traffic automatically routes through remaining devices.
33
What is Power over Ethernet (PoE)?
Technology that sends both electrical power and data over a single Ethernet cable. Common for security cameras, WiFi access points, IP phones.
34
Why share bandwidth in community mesh networks?
Split internet costs, provide backup if one ISP fails, extend coverage to dead zones, community cooperation among tech-savvy neighbors.
35
What determines when to use mesh vs star vs bus topology?
Consider: Cost constraints, reliability requirements, performance needs, number of devices, management complexity, and physical environment.
36
Mac address population of packets when destination lies on different network?
When IP address is identified by a device to be on a different network the layer 2 mac address is populated with the Routers Mac. Mac addresses source and destination IP change at every hop.
37
38
What is computer networking?
The practice of connecting computers and other devices to share resources, exchange data, and communicate across distances. Core functions include resource sharing, communication, data exchange, and distributed computing.
39
Name three different ways you might use networks in a typical day.
Examples: YouTube video streaming, file sharing between devices, email/messaging, cloud storage access, online gaming, video calls, social media, web browsing.
40
When you watch a YouTube video, how does your phone connect to YouTube's servers without a physical cable?
Through multiple network hops: phone → WiFi router → ISP network → internet backbone → YouTube's servers. Each connection uses different technologies (wireless, fiber, etc.) but appears as one continuous connection.
41
Why do internet service providers use multiple paths between locations instead of just one direct connection?
For reliability and redundancy. If one path fails, traffic can automatically reroute through alternative paths. Also provides load balancing and better performance during high traffic periods.
42
Define and give examples of PAN, LAN, MAN, and WAN networks.
- **PAN (Personal Area Network):** 1-10 meters. Example: Bluetooth headphones, smartwatch - **LAN (Local Area Network):** Building/campus. Example: Office network, dorm WiFi - **MAN (Metropolitan Area Network):** City-wide. Example: University campus, regional office network - **WAN (Wide Area Network):** Countries/continents. Example: Internet, corporate multi-site network
43
A university has 50 restaurants across the Denver metro area connected to a regional management center. What network classification is this?
MAN (Metropolitan Area Network) - covers metro Denver area, larger than a single LAN but smaller than multi-state WAN.
44
What's the difference between a campus with multiple buildings vs. two separate company offices in different cities?
Campus = typically one large LAN or MAN (close proximity, single organization). Different cities = WAN (large geographic distance, often multiple service providers involved).
45
Compare star, mesh, and bus topologies - advantages and disadvantages.
- **Star:** Central hub, easy to manage, hub failure affects all - **Mesh:** Multiple connections, high redundancy, expensive and complex - **Bus:** Shared cable, simple/cheap, single point of failure
46
Why do home networks use star topology while internet infrastructure uses mesh?
**Home:** Star is simple, cost-effective, centralized management for few devices. **Internet:** Mesh provides redundancy and load balancing critical for reliability across vast distances and many users.
47
In a large office building, why use switches at the floor level but routers between buildings?
**Switches:** Handle local traffic efficiently within floors (same network segment). **Routers:** Handle traffic between different networks/buildings, provide security boundaries and traffic control.
48
What's the difference between MAC addresses and IP addresses?
- **MAC Address:** Layer 2, hardware-based, only works locally (same network segment), like apartment number - **IP Address:** Layer 3, logical addressing, works across networks, like full mailing address
49
Your laptop learned Room 103's MAC address. You move to the library. Can you still reach Room 103 using that MAC address?
No. MAC addresses only work locally. The library switch doesn't know where that MAC address is, and switches don't forward MAC discovery across routers. Need to use IP addresses for cross-network communication.
50
When sending a packet to a different network, what MAC address goes in the 'local delivery' field?
The router's MAC address (default gateway). The IP address shows the final destination, but the MAC address shows the next local hop - which is always the router when crossing networks.
51
How does your laptop know whether a destination is on the same network or different network?
Uses the subnet mask. The OS compares the network portion of the destination IP with its own network portion. If they match = same network (use destination's MAC). If different = use router's MAC.
52
Your laptop: 192.168.1.100, mask 255.255.255.0. Which are same network: A) 192.168.1.50 B) 192.168.2.50 C) 192.168.1.200?
A and C are same network (first 3 octets match: 192.168.1.x). B is different network (192.168.2.x).
53
Define bandwidth, latency, and packet loss using a YouTube video download example.
- **Bandwidth:** How much data per second (like highway width) - affects download speed - **Latency:** Time for each packet to travel (like travel time) - affects responsiveness - **Packet Loss:** Percentage of lost packets (like lost mail) - causes retransmissions
54
High bandwidth vs. high latency - what's the difference in how they affect downloads?
**High bandwidth:** Big jumps in download progress. **High latency:** Time delays between those jumps. You can have fast downloads with slow response times, or slow downloads with quick response times.
55
Gaming vs. video streaming - which cares more about latency vs. bandwidth?
**Gaming:** Latency more critical (need quick response to button presses). **Video streaming:** Bandwidth more critical (need sustained data flow), though both matter.
56
When downloading a video broken into 70,000 packets, do they all follow the same path and arrive in order?
No. Packets can take different paths through the internet and arrive out of order. Your computer reassembles them using sequence numbers before saving the complete video file.
57
Who handles packet reassembly - the application (like YouTube app) or the operating system?
The OS networking stack handles packet reassembly and sequencing, then delivers the complete data to the application. Apps don't have to worry about packet-level details.
58
Why do we need BOTH switches AND routers in networks?
- **Switches:** Handle local traffic within networks using MAC addresses (Layer 2) - **Routers:** Connect different networks using IP addresses (Layer 3) - Different layers, different functions - both essential for complete networking
59
In a campus network, what's the data flow from your laptop to a web server?
Laptop → Switch (local building) → Router (campus gateway) → ISP router → Internet backbone → Web server's router → Web server's switch → Web server
60
How do wireless access points fit into the switch/router hierarchy?
Access points act like 'wireless switches' - they handle wireless clients but still connect to wired switches, which connect to routers. They extend the network rather than replace switches.
61
Compare client-server vs. peer-to-peer network architecture.
- **Client-Server:** Centralized servers provide services, easier management/security, single point of failure - **Peer-to-Peer:** Each device can be client and server, distributed/resilient, harder to manage - Most internet services use client-server (YouTube, Google, etc.)
62
In the McDonald's restaurant example, classify each level: individual restaurant, Denver metro region, global corporation.
- **Individual restaurant:** LAN (local devices, registers, office, customer WiFi) - **Denver metro region:** MAN (50 restaurants across metro area) - **Global corporation:** WAN (40,000 restaurants worldwide)
63
Identify the network problem: 'Download starts fast but keeps pausing to buffer'
Bandwidth problem - not enough sustained data flow to keep up with consumption.
64
Identify the network problem: 'Download is consistently slow but steady'
Bandwidth problem - the 'pipe' isn't wide enough for fast data transfer.
65
Identify the network problem: 'Everything feels delayed when you click buttons'
Latency problem - high round-trip time between your actions and server responses.

Computer Networking (1 decks)

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