Fundamentals of computer networks: Ethernet

The idea

Ethernet is the family of protocols and standards used for wired local area networks (LANs). It defines how devices on a wired network format and transmit data frames, and how they are addressed using MAC addresses so frames reach the correct device. Ethernet typically connects computers to a switch using copper cable such as twisted pair, or fibre for longer or faster links. It is a wired standard, so it is contrasted with Wi-Fi, which is the wireless LAN standard. In a multiple-choice question you may be asked what Ethernet is used for, what type of network it serves, or how it differs from wireless. The key points to hold are: wired, local area network, uses cables and switches, and uses MAC addressing.

What earns the marks

• Identifies Ethernet as a set of protocols or standards for wired local area networks.
• States that Ethernet uses cabling, such as twisted pair or fibre, to connect devices.
• Explains that Ethernet uses MAC addresses to identify devices and deliver frames on the LAN.
• Contrasts Ethernet (wired) with Wi-Fi (wireless) as the alternative LAN technology.
• Selects the option describing Ethernet's role rather than a wireless or wide-area technology.

Common mistakes and how to put them right

• Treating Ethernet as a wireless technology.

  Put it right: Ethernet is the wired LAN standard, while Wi-Fi is the wireless one.

• Confusing Ethernet with the internet.

  Put it right: Ethernet is a LAN technology, not the global network itself.

• Assuming Ethernet needs no addressing.

  Put it right: Ethernet frames use MAC addresses to reach the correct device on the LAN.

Exam tips

• Link Ethernet to the words wired, LAN and MAC address to trigger the right answer.
• If an option mentions wireless or Wi-Fi, check whether the question is really about Ethernet before choosing it.
• Use the contrast with Wi-Fi to eliminate distractors quickly.