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LabsProtocolsOSI Map

Current Labs

Subnet VisualizerBinary ConverterTCP HandshakeOSI ModelDNS FlowRoutingARP Broadcast

Reference

Tools

Local MVP mode

Mock data only. Auth, payments, storage, and APIs are represented by contracts.

Learning workspace

Data Link Layer

ARP Broadcast Lab

Watch a host discover the MAC address behind a local IPv4 address.

ARP broadcast lab

Discover the MAC address needed to deliver a frame inside one LAN.

cache
Host A checks ARP cache

Host A

CHECKING

192.168.1.10

AA:AA:AA:AA:AA:10

LAN Switch

Layer 2

LAN segment
Layer 2 forwarding

Host B

192.168.1.25

BB:BB:BB:BB:BB:25

Host C

192.168.1.44

CC:CC:CC:CC:CC:44

Host A ARP cache

cache miss
IP addressMAC address
192.168.1.25unknown

No usable MAC address yet. Host A must ask with ARP.

Frame details

The cache lookup misses. Host A must ask the LAN.

local decision

Check cache

Host A checks ARP cache

Host A knows Host B's IP address, but it does not know Host B's MAC address.

Why it matters

Ethernet delivery needs a destination MAC address before any local frame can be sent.

Visible result

The cache lookup misses. Host A must ask the LAN.

Discovery flow

1/8

Check cache

Host A knows Host B's IP address, but it does not know Host B's MAC address.

ARP resolves an IPv4 address to the Ethernet MAC address needed on the local network.

Quick practice

Pause after the broadcast. Which hosts receive the ARP Request, and which host is allowed to reply?