Hub Switch Router

Hub Switch Router

By At June 08, 2025 0


Here's a FAANG-level complete preparation guide for Hub vs Switch vs Router, covering Basic, Intermediate, and Advanced levels with:

  • Conceptual differences

  • Real-world use cases

  • System design relevance

  • Sample Interview Q&A with increasing complexity

  • Visuals and analogies

🔰 1. Basic Level: Concepts & Differences

Feature

Hub

Switch

Router

OSI Layer

Physical (Layer 1)

Data Link (Layer 2)

Network (Layer 3)

Traffic Type

Broadcast to all ports

Unicast based on MAC addresses

Routes packets by IP address

MAC Table

❌ No

✅ Yes

❌ Not needed (uses routing table)

Speed

Shared bandwidth

Dedicated per port

Routes between networks

Intelligence

Dumb (no learning)

Learns MACs, filters traffic

Chooses best path using routing protocols

Use Case

Small LANs (obsolete)

LANs for data transfer

Connect different networks (LAN ↔ WAN)

📚 Real-World Example

🧠 Analogy:

  • Hub: Loudspeaker → sends data to everyone

  • Switch: Receptionist → sends info to exact recipient

  • Router: Google Maps → finds best path between two locations

✅ 2. Intermediate Level: Use in System Design

Scenario

Device

Why

Connecting multiple IoT devices in a smart home

Switch

Reduces network congestion, efficient MAC filtering

Sending data across cities/data centers

Router

Needed for IP-level routing and security policies

Old computer labs in schools

Hub (legacy)

Cheap, simple—but inefficient

❓ 3. Interview Questions: Categorized

🔹 Beginner Level Questions

  1. Q: What is the difference between a hub and a switch?
     A: Hub broadcasts to all ports; switch forwards only to intended MAC address.

  2. Q: At what OSI layer does a router operate?
     A: Layer 3 (Network layer).

  3. Q: Why is a switch preferred over a hub?
     A: Less collisions, better performance, full duplex support, MAC address learning.

🔹 Intermediate Level Questions

  1. Q: What happens when a switch receives a frame with a destination MAC not in its table?
     A: It floods the frame to all ports except the incoming one.

  2. Q: Can a router work without a switch?
     A: Yes, in small networks. Routers often include a built-in switch for basic LAN connectivity.

  3. Q: How does a switch prevent broadcast storms?
     A: Using Spanning Tree Protocol (STP) to prevent loops.

🔹 Advanced Level (FAANG / System Design Focus)

  1. Q: Design a secure enterprise network — what role do switches and routers play?
     A:

    • Switches for internal segment isolation (VLANs), MAC-level security

    • Routers for inter-VLAN routing, firewalling, NAT, and external communication

  2. Q: What happens during ARP request-response across switches and routers?
     A:

    • Switch forwards ARP broadcast within VLAN

    • Router responds with its MAC for default gateway if target IP is external

  3. Q: How do you optimize traffic flow in a data center using routers and switches?
     A:

    • Use Layer 3 switches (routing-capable switches) for speed

    • Apply ECMP (Equal-Cost Multi-Path), BGP, OSPF in routers for high availability

    • Segment with VLANs, VXLANs, SDN for scalable, isolated traffic

🧪 Sample Scenario Question

Q: You're designing a video-streaming platform with edge caching. How do switches and routers fit in?

A:

  • Switch: Local device-to-device streaming within data centers

  • Router: Routing between edge locations, CDN nodes, and user ISPs

  • Use QoS (Quality of Service) on switches/routers to prioritize streaming packets

🔍 Bonus: Debugging & Networking FAANG Questions

  1. How would you debug a case where internal microservices can’t reach the internet?

    • Check switch configuration (port VLAN)

    • Check router NAT/firewall rules

    • Check ARP/routing tables

  2. How do Layer 2/3 devices impact latency in high-frequency trading systems?

    • Switches introduce microsecond delays; cut-through switching may be used

    • Routers with complex ACLs can introduce higher latency—optimize with minimal hops

📦 Interview Prep Tips

✅ Hands-On:

  • Use tools like Cisco Packet Tracer, GNS3, or Wireshark

  • Create small topologies with routers/switches to understand behavior

✅ Study Protocols:

  • STP (Switch)

  • VLAN/VTP

  • ARP, NAT, DHCP (Router)

  • Routing protocols: RIP, OSPF, BGP

✅ System Design Angle:

  • Understand Layer 2 vs Layer 3 roles in microservices, CDN, edge computing, VPCs

📘 Suggested YouTube Channels

  • NetworkChuck – Beginner to Advanced Networking

  • David Bombal – Real labs & packet capture demos

  • Jeremy’s IT Lab – CCNA-level but FAANG-relevant

  • Hussein Nasser – System Design with real-world protocols





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