A gateway is a network interconnectivity device that translates different communication protocols and is used to
connect dissimilar network technologies. It provides greater functionality than a router or bridge because a
gateway functions both as a translator and a router. Gateways are slower than bridges and routers. A gateway
is an application layer device.
Answer option B is incorrect. A router is an electronic device that interconnects two or more computer
networks. It selectively interchanges packets of data between them. It is a networking device whose software
and hardware are customized to the tasks of routing and forwarding information. It helps in forwarding data
packets between networks.
Answer option C is incorrect. A bridge is an interconnectivity device that connects two local area networks
(LANs) or two segments of the same LAN using the same communication protocols, and provides address
filtering between them. Users can use this device to divide busy networks into segments and reduce network
traffic. A bridge broadcasts data packets to all the possible destinations within a specific segment. Bridges
operate at the data-link layer of the OSI model.
Answer option D is incorrect. A switch is a network device that selects a path or circuit for sending a data unit
to its next destination. It is not required in smaller networks, but is required in large inter-networks, where there
can be many possible ways of transmitting a message from a sender to destination. The function of switch is to
select the best possible path.
On an Ethernet local area network (LAN), a switch determines from the physical device (Media Access Control
or MAC) address in each incoming message frame which output port to forward it to and out of. In a wide area
packet-switched network, such as the Internet, a switch determines from the IP address in each packet which
output port to use for the next part of its trip to the intended destination.

The 802.11e standard is a proposed enhancement to the 802.11a and 802.11b wireless LAN (WLAN)
specifications. It offers quality of service (QoS) features, including the prioritization of data, voice, and video
transmissions. 802.11e enhances the 802.11 Media Access Control layer (MAC layer) with a coordinated time
division multiple access (TDMA) construct, and adds error-correcting mechanisms for delay-sensitive
applications such as voice and video. Answer option D is incorrect. 802.11h refers to the amendment added to
the IEEE 802.11 standard for Spectrum and Transmit Power Management Extensions.
Answer option B is incorrect. 802.11n is an amendment to the IEEE 802.11-2007 wireless networking standard
to improve network throughput over the two previous standards - 802.11a and 802.11g - with a significant
increase in the maximum raw data rate from 54 Mbit/s to 600 Mbit/s with the use of four spatial streams at a
channel width of 40 MHz. Answer option A is incorrect. IEEE 802.15 is a working group of the IEEE 802 and
specializes in Wireless PAN (Personal Area Network) standards. It includes seven task groups, which are as
follows:
1.Task group 1 (WPAN/Bluetooth)
2.Task group 2 (Coexistence)
3.Task group 3 (High Rate WPAN)
4.Task group 4 (Low Rate WPAN)
5.Task group 5 (Mesh Networking)
6.Task Group 6 (BAN)
7.Task group 7 (VLC)