NETWORK 007 (6) (DEC)

Which of the following terms defines a wireless LAN transmission technique in which devices use multiple antennae to increase transmission speeds? MIMO TDMA PAN Ant+

A. Multiple input and multiple output (MIMO) calls for the use of two or more antennae, enabling wireless devices to effectively multiplex signals, hereby increasing their transmission speeds. Time Division Multiple Access (TDMA) is a communication technique that splits a frequency into multiple time slots, enabling it to carry multiple data streams. A personal area network (PAN) provides communication among devices associated with a single person, such as smartphones. Ant+ is a wireless protocol that is typically used to monitor data gathered by sensors, such as those in cardiac pacemakers.

Near-field communication (NFC) is a short-range wireless technology that is designed to facilitate communications between two devices within which of the following distances from each other? 4 millimeters 4 centimeters 4 decimeters 4 meters

B. NFC is designed to provide wireless communication between devices up to 4 cm apart, such as smartphones and payment systems.

Which of the following IEEE wireless LAN standards provides the greatest possible throughput? 802.11a 802.11ac 802.11b 802.11g 802.11n

B. The IEEE 802.11ac standard provides the greatest possible throughput, at up to 1.3 Gbps. The 802.11n standard runs at speeds up to 600 Mbps. The 802.11a and 802.11g standards run at up to 54 Mbps. The 802.11b standard runs at up to 11 Mbps.

Which of the following IEEE wireless LAN standards uses the Direct Sequence Spread Spectrum (DSSS) signal modulation technique? 802.11a 802.11b 802.11 g 802.11n 802.11ac

B. The IEEE 802.11b standard calls for DSSS signal modulation. All of the other standards listed call for Orthogonal Frequency-Division Multiplexing (OFDM) encoding.

In its physical implementation, a LAN using a logical ring topology most closely resembles which of the following physical topologies? Bus Mesh Star Ad hoc

C. In a logical ring topology, the signal path leads from each node to the next one, but physically, the network resembles a star, with each node connected to a central nexus. Signals travel from one node to the nexus, then to the next node, and then back to the nexus, and so on. A logical ring could not be implemented on a physical bus topology. A mesh topology could conceivably host a logical ring, but this would be highly impractical on a LAN. Ad hoc is a wireless topology that is not applicable in this situation.

Which of the following is the fastest speed achievable by a wireless LAN using the currently ratified IEEE 802.11 standards? 54 Mbps 600 Mbps 1.3 Gbps 2.6 Gbps

C. The 802.11ac standard defines a wireless LAN running at a speed of up to 1.3 gigabits per second (Gbps). None of the other 802.11 standards call for speeds beyond 600 Mbps. No currently ratified standard enables speeds of 2.6 Gbps.

Which of the following is not a technology typically used for a personal area network (PAN)? Bluetooth Z-Wave NFC ISDN

D. Integrated Services Digital Network (ISDN) is a wide area networking technology that uses the telephone infrastructure to provide a high-speed dial-up service. It is therefore not suitable for use on a PAN. Bluetooth, Z-Wave, and near-field communication (NFC) are all short-range wireless technologies that are capable of proving communications between PAN devices.

Which of the following technologies associated with the Internet of Things (IoT) is often used to identify pets using embedded chips? Z-wave Bluetooth NFC RFID

D. Radio-frequency identification (RFID) uses tags containing data, frequently embedded in pets, which can be read using electromagnetic fields. Z-wave is a short-range wireless technology, frequently used for home automation. Bluetooth is a short-range wireless protocol, frequently used for computer peripherals and personal area networks (PANs). Near-field communication (NFC) provides wireless communication over ranges of 4 cm or less, and it is often used for payment systems.

What is the maximum channel width possible using wireless networking equipment based on the ratified IEEE 802.11 standards? 20 MHz 40 MHz 80 MHz 160 MHz

D. The 802.11ac standard defines the bonding of up to eight 20 MHz channels, for a total possible channel width of 160 MHz. The 802.11n standard can bond up to two channels, for a 40 MHz width. Earlier standards are limited to a single 20 MHz channel.

Alice is attempting to deploy an IEEE 802.11b/g wireless LAN on the fifth floor of a ten-story office building that is surrounded on all sides by other office buildings, all of which seem to be running many wireless LANs. Scanning the 2.4 GHz band, she sees literally dozens of networks, spread across all of the available channels. As a result, her wireless devices have trouble connecting to their access point, and when they do, they achieve only low speeds. Choose the two tasks from the following list that Alice should perform to enable the wireless clients to connect to the network most reliably. (Choose two correct answers.) Upgrade all of the wireless network devices to IEEE 802.11n. Configure the wireless devices to use the 5 GHz band. Configure all of the network devices to use WPA2 encryption with AES. Configure the access point to suppress SSID broadcasts. Upgrade all of the network devices to the latest firmware.

A and B. Upgrading the devices to 802.11n will enable them to use the 5 GHz band and evade the traffic generated by the surrounding networks. Configuring the devices to use the 5 GHz band will provide many more channels to choose from and will avoid the interference from the surrounding 2.4 GHz networks. The type of encryption that a wireless network uses has no bearing on the ability of the devices to avoid the interference generated by surrounding networks. Suppressing SSID broadcasts will not help the devices to connect to the network. Upgrading the firmware on the devices is not likely to have any effect on the connection problems when they are the result of interference from other networks.

On an Ethernet network using the star topology, which of the following devices can function as the cabling nexus that forms the figurative center of the star? (Choose all correct answers.) Hub Router Switch All of the above

A and C. A hub or a switch can function as the cabling nexus at the center of a star topology. Each of the devices on the network is connected by a cable to a hub or switch. Routers are used to connect networks to each other; they cannot function as the center of a star topology.

Which of the following network topologies are used by wireless local area networks (WLANs)? (Choose all correct answers.) Ad hoc Bus Infrastructure Star

A and C. WLANs can use the ad hoc topology, in which devices communicate directly with each other, or the infrastructure topology, in which the wireless devices connect to an access point. The bus and star topologies are used by wired networks only.

Which of the following wireless networking technologies will never experience interference from a 2.4 GHz wireless telephone? (Choose all correct answers.) IEEE 802.11a IEEE 802.11b IEEE 802.11g IEEE 802.11n IEEE 802.11ac

A and E. IEEE 802.11b, 802.11g, and 802.11n networks all can use the 2.4 GHz frequency band for their transmissions, which can experience interference from a wireless telephone using the same frequency. IEEE 802.11a and IEEE 802.11ac, however, use the 5 GHz band, which will not experience interference from a 2.4 GHz phone.

Which of the following wireless networking standards are capable of using only the 5 GHz frequency? (Choose all correct answers.) IEEE 802.11a IEEE 802.11b IEEE 802.11g IEEE 802.11n IEEE 802.11ac

A and E. The IEEE 802.11a and IEEE 802.11ac standards can use the 5 GHz band only. IEEE 802.11b and IEEE 802.11g can use the 2.4 GHz band only. IEEE 802.11n can use either the 2.4 or 5 GHz band.

Which of the following are possible reasons why the 5 GHz frequency tends to perform better than the 2.4 GHz frequency on a wireless LAN? (Choose all correct answers.) The 5 GHz frequency has more channels than the 2.4 GHz frequency. The 5 GHz frequency supports longer ranges than the 2.4 GHz frequency. The 5 GHz frequency conflicts with fewer common household devices than the 2.4 GHz frequency. The 5 GHz frequency transmits at faster speeds than the 2.4 GHz frequency.

A, C, and D. The 5 GHz frequency has 23 channels available in the United States, while the 2.4 GHz frequency has only 11. Many household devices, such as cordless telephones, use the 2.4 GHz frequency band, but relatively few devices use the 5 GHz band. Higher frequencies typically support faster transmission speeds, because with all other conditions equal, they can carry more data in the same amount of time. The 5 GHz frequency typically has a shorter range than 2.4 GHz, because it is less able to penetrate barriers.

Which of the following Ethernet physical layer options does not use the star topology? 10Base2 10Base-T 100Base-TX 1000Base-T

A. 10Base2 is the physical layer specification for Thin Ethernet, which uses coaxial cable in a bus topology. 10Base-T, 100Base-TX, and 1000Base-T all use twisted pair cable in a star topology.

Which of the following topologies requires the installation of terminating resistors at two locations? Bus Star Ring Mesh

A. A bus topology requires terminating resistors at each end of the bus, to remove signals as they reach the end of the cable and prevent them from reflecting back in the other direction and interfering with newly transmitted signals.

An electrician installing a new light fixture accidentally severs one of the LAN cables running through the dropped ceiling space. With which topology would the severed cable cause the greatest amount of disturbance to the network? Bus Star Logical ring Mesh

A. A cable break in a bus topology would split the network into two halves, preventing the nodes on one side of the break from communicating with those on the other. In addition, both halves of the network would be left with one unterminated end, which would prevent the computers on each side of the break from communicating effectively. A cable break in a star or logical ring topology would only interrupt the connection of a single computer to the network. The mesh topology is not often used for LANs, but redundant network connections are a characteristic of mesh networks, which means that a single cable break would have no effect on the network at all.

Which of the following is typically not an example of the Internet of Things (IoT)? A key fob that unlocks your car A smartphone home automation app A remotely monitored cardiac pacemaker A seismic early warning system

A. A key fob that unlocks your car is typically a short-range radio or infrared (IR) device that does not use the Internet for its communications. Each of the other examples describes a device with an IP address that uses the Internet to communicate with a controller or monitoring station.

Alice has constructed a five-node failover cluster in which all five servers are connected to a hard disk array using a dedicated Fibre Channel network. Which of the following terms describes this network arrangement? SAN PAN WAN MAN

A. A storage area network (SAN) is a network that is dedicated to carrying traffic between servers and storage devices. A personal area network (PAN) provides communication among devices associated with a single person, such as smartphones. A wide area network (WAN) is a network that connects devices or networks at different geographic locations. A metropolitan area network (MAN) is a type of WAN that connects devices within a limited geographic area.

On an IEEE 802.11b/g/n wireless network running at 2.4 GHz with multiple access points, the traditional best practice is to use channels 1, 6, and 11, with no two adjacent access points configured to use the same channel. Which of the following is the real reason why this is a good plan? Channels 1, 6, and 11 are the only three channels with frequencies that do not overlap. Channels 1, 6, and 11 have more bandwidth than the other channels. Channels 1, 6, and 11 have greater ranges than the other channels. Channels 1, 6, and 11 are the default settings on most wireless devices.

A. The 22 MHz channels in the 2.4 GHz band are spaced 5 MHz apart, which means that they overlap. Channels 1, 6, and 11 are the only three channels that are distant enough from each other not to overlap. Therefore, they do not interfere with each other. Channels 1, 6, and 11 do not differ from the other channels in their bandwidth or their transmission range. Each wireless device can be set to use only one channel. Therefore, channels 1, 6, and 11 cannot all be the default setting.

Which of the following cabling topologies was used by the first Ethernet networks? Bus Ring Star Mesh

A. The first Ethernet networks used a physical layer implementation commonly known as Thick Ethernet or 10Base5. The network used coaxial cable in a bus topology. Later Ethernet standards use twisted pair cable in a star topology. Ethernet has never used a ring or mesh topology.

Which type of network connects local area networks (LANs) in distant locations? WAN LAN MAN CAN

A. WANs (wide area networks) connect LANs that are geographically distant. A LAN (local area network), as the name implies, is a group of computers, not other LANs, and it is contained within a small area. MANs (metropolitan area networks) connect LANs in a single metropolitan area; they are not confined to a small area. A MAN is typically larger than a LAN but smaller than a WAN. A campus area network (CAN) typically includes a group of adjacent buildings, such as those of a corporation or university.

Which of the following network types are typically wireless? (Choose all correct answers.) WAN PAN SAN WLAN

B and D. Personal area networks (PANs) connect devices associated with a single person, such as smartphones, and are nearly always wireless. Wireless local area networks (WLANs) are wireless by definition. Wide area networks (WANs) typically span long distances and are typically wired, at least in part. Storage area networks (SAN) require high performance levels and are nearly always wired.

Which type of network is typically confined to a small area, such as a single room, floor, or building? WAN LAN MAN CAN

B. A local area network (LAN), as the name implies, is a group of computers contained within a small geographic area. WANs (wide area networks) connect LANs that are geographically distant. MANs (metropolitan area networks) are not confined to a small area; they are typically larger than a LAN but smaller than a WAN. A campus area network (CAN) typically includes a group of adjacent buildings, such as those of a corporation or university.

Ralph is having trouble accessing the Internet this morning and calls his colleague Ed in another department to find out if he's experiencing the same problem. Ed says he's having no problem accessing the Internet, but that might not mean anything because they might be on different subnets. Ralph asks Ed how to tell if they're on different subnets. Ed asks Ralph to read him his IP address. Ralph's address is 192.168.176.171, and Ed says his is 192.168.176.195. Both of them are using the same subnet mask: 255.255.255.224. Are the two men working on the same subnet? No, they are not on the same subnet. Ralph's subnet address is 192.168.176.192, and Ed's subnet address is 192.168.176.160. No, they are not on the same subnet. Ralph's subnet address is 192.168.176.160, and Ed's subnet address is 192.168.176.192. Yes, they are on the same subnet. The subnet address for both is 192.168.176.192. Yes, they are on the same subnet. The subnet address for both is 192.168.176.160.

B. A subnet mask of 255.255.255.224 indicates that the systems are using a Class C address that has been subnetted using a 3-bit subnet identifier. When you convert the last byte of the IP addresses to binary form, you get 10101011 for Ralph's and 11000011 for Ed's. Because the first three bits (the subnet identifiers) are different, the two are on different subnets. Convert the subnet addresses 10100000 and 11000000 back to binary, and you get their respective subnet addresses: 192.168.176.160 for Ralph and 192.168.176.192 for Ed.

Which of the following wireless networking standards is capable of supporting speeds of 54 Mbps and is also backward compatible with IEEE 802.11b? IEEE 802.11a IEEE 802.11 g IEEE 802.11n Bluetooth IEEE 802.11

B. IEEE 802.11g supports transmission speeds up to 54 Mbps, and it is backward compatible with 802.11b equipment. IEEE 802.11 cannot run at 54 Mbps, and while 802.11a can, it is not compatible with 802.11b. IEEE 802.11n cannot run at 54 Mbps, though it can run at faster speeds. Bluetooth is not compatible with any of the IEEE 802.11 standards.

How do wireless networking devices conforming to the IEEE 802.11n and 802.11ac standards achieve transmission speeds greater than 72.2 Mbps? By using direct sequence spread spectrum (DSSS) modulation By using multiple antennae to transmit several data streams simultaneously By using frequencies in the 5 GHz band By sacrificing transmission range for speed

B. The IEEE 802.11n and 802.11ac standards support a transmission technique called multiple input and multiple output (MIMO), which combines the bandwidth of multiple data streams to achieve greater throughput. IEEE 802.11n and 802.11ac do use the 5 GHz band, but this in itself does not yield greater transmission speeds. The specified standards do not call for the use of DSSS modulation, nor do they sacrifice range for speed. In fact, 802.11n and 802.11ac networks can achieve greater ranges than the previous technologies.

Which of the following wireless LAN standards include the ability to use multiple input and multiple output (MIMO) antennae? (Choose all correct answers.) IEEE 802.11a IEEE 802.11b/g IEEE 802.11n IEEE 802.11ac

C and D. Both the IEEE 802.11n and 802.11ac standards include MIMO, which enables them to effectively multiplex signals using multiple antennae. This capability was first introduced in the 802.11n standard, so the 802.11a and 802.11b/g standards do not support it.

Which of the following topologies provides the greatest number of redundant paths through the network? Star Ring Mesh Bus

C. A mesh topology is one in which every node is directly connected to every other node, therefore providing complete redundancy through the network. In a star topology, each node is connected to a central nexus, providing each with a single path to the rest of the network. In a ring topology, each node is connected to two other nodes, providing two possible paths through the network. In a bus topology, nodes are chained together in a line, providing no redundancy.

Which of the following topologies enables wireless devices to access resources on a wired network? Ad hoc Star Infrastructure Bus

C. An infrastructure topology uses a wireless access point (AP) to connect wireless devices to a wired network. An ad hoc topology connects wireless devices to each other, without connecting to a wired network. The star and bus topologies do not support wireless devices.

Ralph is performing a site survey for a wireless LAN installation in a warehouse with two offices at either end of the building, approximately 300 feet apart. If he installs a single access point in the center of the warehouse, equidistant from the two offices, which of the following standards should he look for when purchasing hardware so that workstations in both offices will be able to connect to the network at the best possible speed? IEEE 802.11a IEEE 802.11g IEEE 802.11n IEEE 802.11ac

C. Wireless networks using equipment based on the IEEE 802.11n standard can span indoor distances of up to 175 feet at speeds up to 600 Mbps. An 802.11ac network can run at faster speeds—up to 1.3 Gbps—but it is limited to approximately 115-foot distances. Networks using 802.11g equipment can span 150 feet, but they run at only a maximum of 54 Mbps. An 802.11a network cannot span more than 75 feet, and it runs at no more than 54 Mbps.

Which of the following statements about a wired local area network (LAN) is true? Wired LANs support only the star topology. Wired LANs support only the star and bus topologies. Wired LANs support only the star and ring topologies. Wired LANs can support ring, bus, or star topologies.

D. A wired LAN is a group of computers within a small area, connected by a common network medium. A wired LAN can be configured using a ring, bus, or star topology.

A wireless access point (AP) enables computers equipped with wireless network interface adapters to function in which of the following topologies? Star Ad hoc Bus Infrastructure

D. A wireless access point is a device with a wireless transceiver that also connects to a standard cabled network. Wireless computers communicate with the access point, which forwards their transmissions over the network cable. This is called an infrastructure topology. A star or bus network requires the computers to be physically connected to the network cable, and an ad hoc topology is one in which wireless computers communicate directly with one another.

Ralph has been contracted to consult for a company that wants to update its legacy Ethernet network to Gigabit Ethernet. On examining the site, he discovers that the network is still using coaxial-based Thin Ethernet. What change in network topology must occur to upgrade the existing network to Gigabit Ethernet using unshielded twisted pair (UTP) cable? Bus to ring Ring to star Star to bus Bus to star Star to ring

D. All coaxial-based Ethernet networks, including Thin Ethernet, use a bus topology. All UTP-based Gigabit Ethernet networks use a star topology. Therefore, an upgrade from coaxial to UTP cable must include a change in topology from bus to star.

Which of the following components are required for two computers to communicate using an IEEE 802.11 wireless LAN using an ad hoc topology? A router connected to the Internet A wireless access point An external antenna None of the above

D. An ad hoc topology describes wireless computers that communicate directly with each other, without the need for any hardware other than their wireless network adapters. The ad hoc topology therefore does not require a router, an Internet connection, an access point, or a special antenna.

When designing a wireless LAN installation, which of the following are valid reasons to install a unidirectional antenna in an access point, rather than an omnidirectional one? (Choose all correct answers.) The access point will be located against an outside wall. There are many interior walls between the access point and the most distant workstation. A unidirectional antenna can be focused to a specific signal pattern width. All of the above.

D. By placing a unidirectional antenna against an outside wall, you can limit network access to users inside the structure. Unidirectional antennae provide greater signal strength than omnidirectional antennae, enabling their signals to penetrate more interior walls. It is possible to focus a unidirectional antenna to a wider or narrower signal pattern.

What is the term for the technology implemented in the IEEE 802.11ac standard that enables a wireless device to transmit multiple frames to multiple clients simultaneously? MIMO Channel bonding CSMA/CA MU-MIMO

D. The multiple input and multiple output (MIMO) technology introduced in the IEEE 802.11n standard enables wireless devices to transmit and receive signals using multiple antennae simultaneously. The Multiuser MIMO (MU-MIMO) variant defined in the 802.11ac standard advances this technique by enabling wireless devices to transmit multiple frames to different users simultaneously, using multiple antennae. Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) is a media access control mechanism used by all 802.11 networks. Channel bonding is a wireless networking technique that combines channels to increase bandwidth.

Which of the following is a cellular communication technology that is virtually obsolete in the United States? GSM CDMA CSMA/CD TDMA

D. Time Division Multiple Access (TDMA) is a communication technique that splits a frequency into multiple time slots, enabling it to carry multiple data streams. Commonly used in 2G cellular systems, the major U.S. carriers no longer use it in their 3G systems. Code Division Multiple Access (CDMA) and Global System for Mobile Communication (GSM) are alternative communications techniques that are currently used by the major U.S. cellular carriers. Carrier Sense Multiple Access with Collision Detection (CSMA/CD) is a media access control method used by Ethernet networks; it is not a cellular communication technology.

Which of the following topologies is used by the majority of new Ethernet networks installed today? Bus Virtual ring Mesh Hierarchical star

D. Virtually all of the new Ethernet networks installed today use the star or the hierarchical star topology, with one or more switches functioning as a cabling nexus.