Which two networking devices operate at Layer 1 of the OSI model? (Choose two.)
A.
Repeater
B.
Bridge
C.
Switch
D.
Router
E.
Hub
Explanation:
It defines the electrical and physical specifications of the data connection. It defines the
relationship betweena device and a physical transmission medium (e.g. a copper or fiber optical
cable). This includes the layout ofpins, voltages, line impedance, cable specifications, signal
timing, hubs, repeaters, network adapters, host busadapters (HBA used in storage area networks)
and more.”
http://en.wikipedia.org/wiki/OSI_model
In the seven-layer OSI model of computer networking, the physical layer or layer 1 is the first (lowest) layer
The physical layer consists of the basic networking hardware transmission technologies of a network.
It is a fundamental layer underlying the logical data structures of the higher level functions in a network. Due to the plethora of available hardware technologies with widely varying characteristics, this is perhaps the most complex layer in the OSI architecture.
The physical layer defines the means of transmitting raw bits rather than logical data packets over a physical link connecting network nodes. The bit stream may be grouped into code words or symbols and converted to a physical signal that is transmitted over a hardware transmission medium. The physical layer provides an electrical, mechanical, and procedural interface to the transmission medium. The shapes and properties of the electrical connectors, the frequencies to broadcast on, the modulation scheme to use and similar low-level parameters, are specified here.
Within the semantics of the OSI network architecture, the physical layer translates logical communications requests from the data link layer into hardware-specific operations to affect transmission or reception of electronic signals.
Hardware equipment (network node) examples
Network adapter
Repeater
Network hub
Modem
Fiber Media Converter
see https://en.wikipedia.org/wiki/Physical_layer
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