This document defines and describes several common computer networking devices. It explains that network interface cards allow computers to connect to networks by providing a physical connection and MAC address. Hubs broadcast all data to all ports, while switches only send data to the targeted port, improving efficiency. Bridges separate traffic on connected network segments. Routers connect dissimilar networks and make routing decisions. Gateways convert between data formats. Repeaters receive and retransmit signals to extend range. Modems convert digital data to analog signals for telephone line transmission. Media converters connect different cabling types. Wireless access points provide connections to wireless networks.

2. Computer networking devices are units that mediate data in A computer
network and are also called network equipment. Units which are the last
receiver or generate data are called hosts or data terminal equipment.

3.  A network interface card is a computer hardware component designed to
allow computers to communicate over a computer network.
 It is both an OSI layer 1 (physical layer) and layer 2 (data link layer)
device, as it provides physical access to a networking medium and provides
a low-level addressing system through the use of MAC addresses.
 It allows users to connect to each other either by using cables or wirelessly.
 Most motherboards today come equipped with a network interface card in
the form of a controller, with the hardware built into the board itself,
eliminating the need for a standalone card.

4.  Hubs are simple devices that are used in networks that use twisted-pair
cabling to connect devices.
 Hubs can be joined together to create larger networks.
 Hubs simply direct the data packets to all devices connected to the hub,
regardless of whether the data package is destined for the device.
 It means if one station sends it, all the others receive it, but only the
intended recipient listens to it.
 This makes them inefficient devices and can create a performance
bottleneck on busy networks.

5.  Like a hub, a switch connects multiple segments of a network together, but
with one important difference.
 Whereas a hub rebroadcasts anything it receives on one port to all the
others, a switch makes a direct link between the transmitting device and
receiving device.
 Any party not involved in that communication will not receive the
transmission.
 The benefit of a switch over a hub is that the switch increases performance
because it doesn’t suffer from the wasted bandwidth of the extra
transmissions.

6.  A bridge is a network device that connects two similar network segments
together.
 The primary function of a bridge is to keep traffic separated on both sides
of the bridge.
 Traffic is allowed to pass through the bridge only if the transmission is
intended for a station on the opposite side.
 The main reason for putting a bridge in a network is to connect two
segments together, or to divide a busy network into two segments.

7.  A router is a network device
that connects multiple, often
dissimilar, network segments
into an internetwork.
 The router, once connected,
can make intelligent
decisions about how best to
get network data to its
destination based on
network performance data
that it gathers from the
network itself.

8.  Any device that translates one data format to another is called a gateway.
 Some examples of gateways include a router that translates data from one
network protocol to another, a bridge that converts between two
networking systems, and a software application that converts between two
dissimilar formats.
 The key point about a gateway is that only the data format is translated, not
the data itself. In many cases, the gateway functionality is incorporated into
another device.

9.  A repeater is an electronic device
that receives a signal and
retransmits it at a higher level
and/or higher power, or onto the
other side of an obstruction, so that
the signal can cover longer
distances without degradation.
 Because repeaters work with the
actual physical signal, and do not
attempt to interpret the data being
transmitted, they operate on
the physical layer, the first layer of
the OSI model.

10.  Modem (from modulator-demodulator) is a device that turns the digital 1s
and 0s of a personal computer into sounds that can be transmitted over the
telephone lines of Plain Old Telephone Systems (POTS), and once received
on the other side, converts those sounds back into a form used by a USB,
Ethernet, serial, or network connection.
 Modems are generally classified by the amount of data they can send in a
given time, normally measured in bits per second, or "bps".

11.  Media converters are simple networking devices that make it possible to
connect two dissimilar media types such as twisted pair with fibre optic
cabling.
 Media converters support many different data communication protocols
including Ethernet as well as multiple cabling types such
as coaxial, twisted pair, multimode and single-mode fibre optics.
 Media converters are useful in connecting multiple LANs to form one large
"campus area network" that spans over a limited geographic area. As local
networks are primarily copper-based, media converters can extend the
reach of the LAN over single-mode fibre up to 130 kilometres with 1550
nm optics.

12.  Wireless access points (APs) are a transmitter and receiver (transceiver)
device used to create a wireless LAN (WLAN).
 APs are typically a separate
network device with a
built-in antenna, transmitter, and adapter.
 APs use the wireless infrastructure
network mode to provide a connection
point between WLANs and a
wired Ethernet LAN. APs also
typically have several ports allowing
a way to expand the network to support additional clients.
 Depending on the size of the network, one or more APs might be required.

13. In addition to these network connectivity devices, there are several devices
that, while maybe not directly connected to a network, participate in
moving network data. Some of these devices include: Modems ISDN
Terminal Adapters CSU/DSUs

15.  http://computernetworkingnotes.com/comptia-n-plus-study-guide/network-
devices-hub-switch-router.html
 http://www.quepublishing.com/articles/article.aspx?p=101728&seqNum=2
 http://pluto.ksi.edu/~cyh/cis370/ebook/ch07b.htm
 http://www.pearsonhighered.com/samplechapter/0789732548.pdf