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Beginner Topic 10 of 50 Computer Networks

Ethernet

Dominant wired LAN technology using frames.

How it works

Ethernet is the dominant wired LAN technology, defining frame format, MAC addressing, media and speeds from 10 Mbps to 400 Gbps and beyond. A frame carries destination and source MAC addresses, a type field, a payload of up to 1500 bytes and a CRC checksum. Early shared Ethernet used CSMA/CD to handle collisions; modern switched full-duplex links have no collisions.

Step-by-step walkthrough

  1. A frame begins with a preamble to synchronize clocks.
  2. The destination MAC says who should receive it.
  3. The source MAC says who sent it.
  4. The payload carries up to 1500 bytes of data.
  5. A CRC at the end detects corruption.

Where it is used

Offices, homes, data centers and industrial networks use Ethernet over twisted pair or fiber, and power over Ethernet supplies devices with electricity. Wi-Fi bridges to it.

Common pitfall

Duplex mismatches between ports and bad cables cause slowdowns and errors. Loops in switched topologies cause broadcast storms unless spanning tree is enabled. Exceeding the maximum cable length degrades signals. Jumbo frames require every device on the path to support the larger MTU.

Where it fits in the course

Ethernet is topic 10 of 50 in Computer Networks, rated Beginner. It follows MAC Addresses. The next topic is Switches and Hubs.

Practice and explore

How to study this topic

  1. Read the explanation above and restate the definition in your own words.
  2. Open the interactive lesson and answer its mini quiz.
  3. Read the common pitfall, then write a short example that avoids it.
  4. Check your understanding in the Computer Networks quiz, and revisit the topic if you miss a question.

Frequently asked questions

What is Ethernet?
Dominant wired LAN technology using frames. It belongs to Computer Networks and is a beginner-level topic.
Where do people use Ethernet?
Offices, homes, data centers and industrial networks use Ethernet over twisted pair or fiber, and power over Ethernet supplies devices with electricity.
What is the most common mistake with Ethernet?
Duplex mismatches between ports and bad cables cause slowdowns and errors.
What should I learn before this topic?
Start with MAC Addresses, the topic just before it in Computer Networks.
How can I practice it?
Answer the mini quiz in the interactive lesson, then take the Computer Networks quiz.
Is Ethernet hard to learn?
It is a Beginner topic, so it works as an entry point. If the terms are new, read the explanation twice and try the visualizer before the quiz.
How long does it take to learn Ethernet?
Most learners can read the explanation and finish the interactive lesson in under an hour. Fluency comes from applying the idea, so plan a few short practice sessions with the quiz.
Which topics are related to Ethernet?
MAC Addresses, Switches and Hubs, Subnetting are closely connected. The full list is in the related topics section of this page.
What should I study after Ethernet?
Continue with Switches and Hubs, the next topic in Computer Networks.

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