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Critical Device Comparisons
CN

Critical Device Comparisons

Master the fundamental differences between Hubs, Switches, and Routers for interview success.

Hub vs Switch

FeatureHub (Layer 1)Switch (Layer 2)
IntelligenceNone — repeats signal to all portsLearns MAC addresses, forwards selectively
Collision domainSingle (all ports share)Per port (each port is isolated)
DuplexHalf-duplexFull-duplex
BandwidthShared across all portsDedicated per port
EfficiencyLow — collisions waste bandwidthHigh — no collisions

The hub broadcasts everything. If device A sends to device B, every device on the hub gets the signal (and has to ignore it). On a switch, only device B gets the frame — the rest are free to communicate simultaneously.

Switch vs Router

FeatureSwitch (Layer 2)Router (Layer 3)
Address typeMAC addressesIP addresses
ForwardingSwitch fabric (hardware)Routing table + CPU
Network scopeWithin the same LANBetween different networks
Broadcast handlingForwards broadcastsDrops broadcasts (doesn’t propagate)
Default gatewayNoneTypically the gateway for the LAN

A switch connects devices inside one network. A router connects different networks together. Your home “router” is actually a combination: router + switch + WiFi access point + NAT.

Layer 3 Switch

A hybrid device that switches at hardware speed but also routes using IP addresses. Used in large enterprise networks where both high-speed internal switching and inter-VLAN routing are needed. Faster than a traditional router for internal traffic.

Other Comparisons

DeviceLayerFunction
Repeater1Regenerates weak signals (extends distance)
Hub1Multi-port repeater
Bridge2Connects two network segments, filters by MAC
Switch2Multi-port bridge
Router3Routes between networks
Gateway3+Protocol translation between different network types

Q: Why is a Hub a broadcast device?

A: A hub has no intelligence — it doesn’t know MAC addresses. It simply repeats every incoming signal to ALL other ports. This means every device sees every frame, wasting bandwidth.

Q: Can a Switch replace a Router?

A: No. A switch forwards within a LAN using MAC addresses. A router connects different networks using IP addresses. You need a router to reach the internet — your home “router” is actually a router + switch combo.

Q: What is a Layer 3 Switch?

A: A switch that can also route using IP addresses. It combines the wire-speed throughput of a switch with the routing capability of a router. Used for inter-VLAN routing in large enterprise networks.

Q: What’s the difference between a Bridge and a Switch?

A: A bridge has 2 ports and connects two network segments. A switch is essentially a multi-port bridge — it learns MAC addresses and forwards selectively. Switches are faster and more scalable.

My Private Notes

Notes are auto-saved locally to this device.