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Networking Fundamentals · Foundational

100BASE-TX

Fast Ethernet over two pairs of Cat 5 or better UTP at 100 Mbps, up to 100 meters.

Definition

Defined in 802.3u (1995), 100BASE-TX uses pins 1, 2, 3 and 6 like 10BASE-T. It remains common for low-bandwidth devices such as IP phones, printers and building systems.

Example

An access control panel links at 100 Mbps full duplex.

Exam tip

100BASE-TX uses only two pairs; Gigabit needs all four.

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