ROC 3 PT 2 test
The original Ethernet operated at which of the following speeds?
10 Mbps.
The fiber-optic links that usually connect asynchronous transfer mode (ATM) switches operate at which of the following speeds?
155 Mbps.
Which is the largest IEEE 802.11 data frame that can traverse a wireless local area network (WLAN) without fragmentation?
2,346 bytes.
Most wireless office local area networks (LAN) currently operate in what frequency band?
2.4 GHz
What power over Ethernet (PoE) device picks off the direct current (DC) voltage that has been injected into the CAT-5e cable by the injector and makes it available to the equipment through the regular DC power jack?
A DC picker or tap.
What does the term bit loading describe?
A DOCSIS 3.1 feature in which each orthogonal frequency division multiplexing (OFDM) subcarrier can operate at a different modulation order.
When traffic on a local area network (LAN) starts to cause performance problems, what Layer 2 device can be installed to reduce the load by dividing the network into separate segments?
A bridge.
When a process in one computer operates at the same layer as a process in another computer, it is considered
A peer.
Bottom-layer protocols can only support communications between devices that are somehow physically connected. This connection can be described as:
A point-to-point connection.
Data added to a message, that provides information about the message, is called which of the following?
A protocol header.
What test instrument is used to locate and measure interfering narrowband radio frequency (RF) signals in an Institute of Electrical and Electronic Engineers (IEEE) 802.11 wireless local area network (WLAN), among other things?
A spectrum analyzer.
What is a half-duplex device that is only capable of Open Systems Interconnection (OSI) reference model Layer 2 (Data Link Layer) connectivity?
A wireless bridge.
An independent basic service set (IBSS) is also commonly referred to as which one of the following?
Ad hoc network.
What is the least disruptive migration strategy to DOCSIS 3.1 from a previous DOCSIS version?
Adding an orthogonal frequency division multiplexing (OFDM) channel to the downstream frequency spectrum.
Computer busses have two parts:
An address bus and a data bus.
What is multiplexing?
An efficient method of sharing a common medium for the transport of signals over-the-air (OTA) or though metallic and fiber-optic cable.
What causes co-channel interference in a wireless local area network (WLAN)?
An overlap in the signal ranges of access points (AP) or different WLANs operating on the same channels.
Which of the provided voltage standing wave ratios (VSWR) shown here is best for transferring radio frequency (RF) energy between connections?
1.2:1
The lowest layer of a protocol stack communicates with which one of the following
Binary bits.
When first activating Proactive Network Maintenance (PNM) in your network, what is one approach to avoid being overwhelmed by the number of identified problems?
Build a spreadsheet with thresholds set so that the worst performing portion of the network can be identified and corrected first.
What media access control (MAC) method do wireless local area networks (WLAN) use?
Carrier sense multiple access with collision avoidance (CSMA/CA).
What are the two types of orthogonal frequency division multiplexing (OFDM) pilot subcarriers?
Continuous and scattered pilot subcarriers.
What unit of measurement is used to express the gain of an antenna?
Decibels over, or under 1 milliwatt (mW
As a general rule, how does an increase in effective isotropic radiated power (EIRP) relate to the link budget range?
Each 6 decibels (dB) increase in EIRP equates to a doubling of range.
In what direction does an omnidirectional antenna radiate radio frequency (RF) energy?
Equally in all directions around its axis.
What specific problem does a wireless local area network (WLAN) resolve for corporations and home users?
Excessive data cabling.
A Layer 2 switch is used to switch:
Frames.
In addition to amplifying the signal, what else does an amplifier do?
It adds a small amount of noise and distortion that doubles each time the number of cascaded amplifiers double.
What is formed at the Network Layer after header data is added to the data passed down from the layer above (Transport Layer)?
Packets.
What is a characteristic of Profile A, because it is the boot profile, that DOCSIS 3.1 modems first begin receiving when they initialize and register?
Profile A should have relatively low bit loading to ensure that it is received by all modems.
A server is a computer that
Provides resources to other computers.
The classification of software used for telecommuters is referred to as:
Remote access.
You are designing a wireless network to which several functional workgroups are connected. You want to configure your enterprise wireless gateway to allow you to quickly assign identical network access rights to persons within the same workgroup. Which enterprise wireless gateway feature provides this capability?
Role-Based Access Control (RBAC).
How do you troubleshoot a hidden node?
Test for degraded data throughput at all client locations.
When connecting to a wireless local area network (WLAN), what is the most important fact about the service set identifier (SSID)?
That the clients and all access points (AP) must be configured with matching SSIDs
Which type of cable modem termination system (CMTS) table translates (or maps) a node number with a fiber node name?
The Node Configuration Table.
Which of the following is a function of the Session Layer?
To facilitate a step-by-step interaction between two entities.
The Open Systems Interconnection (OSI) Model was developed so that
Users could connect to the Internet using hardware manufactured by any company.
Why are wireless local area networks (WLAN) usually deployed in an access capacity instead of as the network's core layer?
WLANs are generally incapable of meeting the requirements of the network core layer, which needs to be very fast and stable, able to handle a tremendous amount of traffic with little difficulty, and must experience no down time.
Which one of the following Institute of Electrical and Electronics Engineers (IEEE) wireless standards utilizes the 5 gigahertz (GHz) frequency band for its signal transmissions?
802.11n
What device would a wireless local area network (WLAN) administrator install between the access point (AP) or bridge and the network to give indoor local area network (LAN) users as much bandwidth as possible?
A bandwidth control unit (BCU).
What is defined in DOCSIS 3.1 that strengthens the security of cable modem authentication and secures software download features?
A new certificate public key infrastructure (PKI).
Why is a node+0 hybrid fiber/coax (HFC) network design preferred over a node+6 HFC network design?
A node+0 HFC design has no amplifiers, whereas a node+6 HFC design has amplifiers that add noise and distortion to the amplified signal.
What antenna type is ideal for making a point-to-point (P2P) network connection between two office buildings that are across the street from one another?
A semidirectional antenna.
What is a slot time in an Institute of Electrical and Electronics Engineers (IEEE) 802.11 wireless local area network (WLAN)?
A standard period of time which is preprogrammed into the radio and determined by the WLAN technology being utilized.
Which elements of a hybrid fiber/coax (HFC) network are most likely to cause a service outage because of component failure or loss of power?
Amplifiers.
The overall data-carrying capacity of a bus is represented by the unit's
Bandwidth.
Why would a wireless local area network (WLAN) administrator rarely see the "authenticated" step on the access point (AP)?
Because clients pass the authentication stage and immediately proceed into the association stage.
What media access control (MAC) method does Ethernet use?
Carrier sense multiple access with collision detection (CSMA/CD).
Asynchronous transfer mode (ATM) operates at which layers of the Open Systems Interconnection (OSI) Model?
Data Link and Physical Layers.
A network interface card (NIC), aka media access control (MAC) address, resides at the _________ Layer and a logical address resides at the ___________ Layer.
Data Link/Network.
Which of the following is used by bridges to make bridging decisions?
Frame addresses.
The DOCSIS MAC and Upper Layer Protocols Interface (MULPI) specification extends through which layers of the Open Systems Interconnection (OSI) reference model?
Layer 2 through Layer 7.
When two or more nodes share some downstream and upstream channels, and have others unique to each node, then the nodes are in the same Media Access Control (MAC) Domain by virtue of sharing some channels. What are the channels that are unique to each node in the MAC Domain called?
MAC Domain-Cable Modem-Service Groups (MD-CM-SG).
Which of the layers below is most concerned with getting a packet through a network from a source, through intermediate nodes, to the final destination?
Network.
Why should a wireless network administrator consider installing an enterprise wireless gateway in their network?
The enterprise wireless gateway enables the wireless network administrator to manage a large wireless network using only a few central devices instead of a very large number of access points.
Which component of frequency hopping spread spectrum (FHSS) system creates more overhead than any similar component in a direct sequence spread spectrum (DSSS) system?
The interframe spacing.
Where does the modem, operating in DOCSIS 3.1 mode, tune to receive data when the downstream contains an orthogonal frequency division multiplexing (OFDM) channel and single carrier-quadrature amplitude modulation (SC-QAM) channels?
The modem tunes to the OFDM channel and the SC-QAM channels, and receives data on both.
What happens if the cable modem receives two different data carriers at the same time?
The modem will hear unintelligible mush, and neither carrier is received.
When several nodes share the same transmission medium (hub, switch, or radio channel), each node will receive the frame transmitted between client and server, and vice versa. Which node will process the information inside the frame?
The node with a network interface card (NIC) address that matches the destination address in the Ethernet frame header.
Why are the frequency assignments in the Frequency Space Diagram based on the nodes?
The nodes are where the most frequency congestion can occur
What indicates an adaptive equalizer's level of sampling and correction capability?
The number of taps in the delay line.
Basic computer functions such as reading and writing files, and managing input/output (I/O) requests are performed by which one of the following?
The operating system.
In a frequency-hopping spread spectrum (FHSS) system that uses 10 frequencies across a 12 megahertz (MHz) frequency band, what happens if narrowband interference occurs at only one of the 10 frequencies?
The spread spectrum signal remains intact. Instead of being lost, the data on the interfered frequency is retransmitted on one of the other nine frequencies.
On a PreEqualization Analyzer's tap response, what does a digital tap that is less than 10 dB lower than the main tap indicate?
There is a severe micro-reflection in the upstream.
How are interframe spaces used in an Institute of Electrical and Electronics Engineers (IEEE) 802.11 wireless local area network (WLAN)?
They are used to defer a station's access to the medium and provide various levels of priority.
In order for channels to be in the same bonding group, they must meet which of these criteria?
They must be on the same Media Access Control (MAC) Domain.
What purpose do protocols serve in computer networking?
They provide rules for communications.
What was the motivation for the conception of the converged cable access platform (CCAP)?
To combine digital television (DTV) and DOCSIS operations from a common unified platform.
What is the purpose of the cyclic prefix (CP)?
To compensate for micro-reflections in the transmission path by providing a protective interval between successive orthogonal frequency division multiplexing (OFDM) symbols.
Which of the following operating systems (OS) has reliability, functionality, and stability beyond question?
UNIX.
What causes the hidden node problem in a wireless local area network (WLAN)?
When a client (or node) can receive signals from an access point (AP) but an obstacle prevents the client from receiving signals from the other clients that are connected to the network.
When should you consider enabling Request to send/clear to send (RTS/CTS) protocol on a wireless local area network (WLAN)?
When diagnosing network problems and when large frames experience high collision rates across a congested wireless network.
Which statement best describes a network application for which a wireless workgroup bridge is the best suited?
When remote buildings house small groups of wired clients needing wireless access to the main network.
Which wireless client devices require drivers to be installed on the client node?
Wireless client devices on printed circuit (PC) cards that are to be installed in peripheral component interconnect (PCI) or industry standard architecture (ISA) adapters.
Which of the following networks or products use spread spectrum technologies?
Wireless local area networks (WLAN), Bluetooth, and global positioning systems (GPS).
What channel bandwidth is the power level out of a single cable modem termination system (CMTS) RF port based upon?
A 6 MHz bandwidth channel.
Which of the following is the portion of a network that connects other segments or networks to one another?
Backbone.
A significant difference between T1 line and a fractional T1 (FT1) line is
Control over the physical endpoints.
In what manner do radio waves propagate (move) away from the source (antenna)?
In a straight line in all directions at once.
What is the advantage of the multi-profile capability of DOCSIS 3.1 over legacy single profiles?
In multi-profile systems, the data throughput is optimal for the network conditions.
Why are the highest tiers of high-speed data (HSD) service typically a fraction of the DOCSIS downstream capacity?
In order to confidently provide subscribed tier speeds to all customers.
What can be done to increase the coverage area of a wireless local area network (WLAN)?
Increase the transmission power, replace the omnidirectional antenna with a parabolic antenna, and use the 2.4 gigahertz (GHz) radio band instead of the 5 GHz radio band.
What benefits were cited by the broadband cable operators that utilized DOCSIS 3.0 Proactive Network Maintenance (PNM) in their networks?
Increased customer satisfaction and reduced operational expenses.
The typical users of network management and utility software are
Information systems personnel and network administrators.
Which term describes the operation mode of a basic service set (BSS)?
Infrastructure mode.
Which statement describes a bottom layer protocol
It communicates over direct physical links.
Which one of the following conditions occurs when an access point (AP) receives a distant client's signal at a lower power level than that of a nearer client?
Near/Far.
What type of connectivity is needed to connect networks between two buildings located across the street from each other?
Point-to-point (P2P).
T3 and synchronous optical networks (SONET) are considered
Point-to-point link options.
Which one of the following power management modes populates a traffic indication map (TIM) in a basic service set (BSS) or extended service set (ESS)?
Power save polling (PSP) mode.
What distinguishes routers from switches and bridges?
Routers operate on packets; switches and bridges operate on frames.
What Application/Presentation Layer protocol is used by a Windows client retrieving files from a file server?
Server Message Block (SMB).
The layer of the OSI Model that controls the way information flows between processes is which of the following?
Session.
Which type of interframe space provides the highest level of priority network function control over the medium for a short time period?
Short Interframe Space (SIFS).
What is the tradeoff between the fragmenting of packets into shorter fragments versus keeping longer packet fragments?
Shorter packet fragments have lower probability of errors from interference than longer packet fragments, but shorter packet fragments require more error correction.
The Physical Layer is responsible for transmitting and receiving
Signals that represent data bits.
Why is spread spectrum technology used in applications such as Bluetooth wireless personal area networks (WPAN)?
Spread spectrum technology allows wireless networking to create a short range, personal communications network.
Which multi-profile approach establishes a strict hierarchy among the profiles and is the simplest to implement?
Static profile.
What are some common methods used to configure and manage access points (AP)?
Telnet/ssh (secure shell), universal serial bus (USB), and a built-in web server for browser access.
Besides data rates, what is the difference between the Institute of Electrical and Electronics Engineers (IEEE) 802.11a and 802.11b wireless standards?
The 802.11a uses the 5.8 GHz range, and the 802.11b uses the 2.4 GHz range.
What does the "on with threshold" setting of the Request to send/clear to send (RTS/CTS) protocol allow the wireless local area network (WLAN) administrator to control?
To control which frames over a certain size are announced and cleared to send by the stations.
What are the three main conditions that influence the range of a wireless local area network (WLAN)?
Transmission power, antenna type and location, and environment.
What are the responsibilities of the Physical Layer (Layer 1) in the Open Systems Interconnection (OSI) reference model and DOCSIS?
Transmission stream of data bits.
The primary purpose of a Network Layer protocol is to
Transmit packets between source and destination nodes that may not be connected by the same physical link.
How might you confirm the presence of a hidden node on the network?
Turn on the request to send/clear to send (RTS/CTS) protocol and watch for increased network data throughput.
Which of the following describes the process of frequency modulation (FM)?
Vary the signal frequency and hold the signal amplitude constant.
What is the width of direct sequence spread spectrum (DSSS) channels and how far apart are their center frequencies spaced?
22 megahertz (MHz) wide and 5 MHz apart.
How many pre-equalizer taps are used in DOCSIS 3.1?
24.
Field trials have shown that a DOCSIS 3.1 orthogonal frequency division multiplexing (OFDM) channel is how much more resistant to noise and other impairments than legacy DOCSIS channels?
3 decibels (dB).
How many single carrier 256-QAM carriers must be channel bonded to achieve 1,000 Mbps downstream data rates?
32.
Given an access point (AP) with 100 milliwatts (mW) of output power connected through a cable with 3 decibels (dB) of loss to the antenna with a 10 decibels isotropic (dBi) gain, what is the approximate Equivalent Isotropically Radiated Power (EIRP) level from the antenna in mW?
500 mW.
Which of the following Institute of Electrical and Electronics Engineers (IEEE) 802.11 wireless local area network (WLAN) standards specifies both spread spectrum radio frequency (RF) and infrared (IR) transmission technologies?
802.11
Which statement best describes protocol filtering that has been implemented in a wireless bridge?
Allowing or denying wireless traffic using Open Systems Interconnection (OSI) reference model Layer 4 (Transport Layer) ports to filter Layer 7 (Application Layer) applications.
What wireless local area network (WLAN) device can be described as a half-duplex device with intelligence equivalent to that of a sophisticated Ethernet switch?
An access point (AP)
What types of applications are most suitable for time division multiplexing (TDM)?
Applications where the transmitted signal is of a non-continuous duration.
Although there are many different implementations of spread spectrum technology, what are the only types specified by the Federal Communications Commission (FCC) in the Codes of Federal Regulation (CFR), Volume 47, Part 15?
Direct Sequencing Spread Spectrum (DSSS) and Frequency Hopping Spread Spectrum (FHSS).
Where does the DOCSIS 3.1 modem acquire its operating parameters when first powered up or initialized?
From either non-volatile memory or from a valid primary downstream channel.
What is the purpose of the distributed coordination function (DCF) in an Institute of Electrical and Electronics Engineers (IEEE) 802.11 wireless local area network (WLAN)?
It allows all clients on a WLAN to contend for access on the shared radio frequency (RF) transmission medium using the carrier sense multiple access with collision avoidance (CSMA/CA) protocol.
Why is it of concern if a modem is constantly adjusting its output transmission level?
It could indicate an intermittent condition in the network that needs to be identified and corrected.
The ratio of the chipping code to data bits for a direct sequence spread spectrum (DSSS) signal is called which of the following?
Processing gain.
How does radio frequency line-of-sight (RF LOS) differ from visual LOS?
RF LOS is accompanied by a Fresnel zone, a series of concentric ellipsoid-shaped areas around the visual LOS path.
Because the primary job of the OSI Presentation Layer is to deal with the format of computing information, the Presentation Layer would be better named the:
Representation layer.
In which Open Systems Interconnection (OSI) reference model layer do wireless local area networks (WLAN) operate?
The Data Link Layer
A bridge normally operates at which of the following layers of the Open Systems Interconnection (OSI) Model?
The Data Link Layer.
In order to keep good records, tables are constructed describing what is constructed in the cable modem termination system (CMTS). Which table provides the CMTS enough information to ensure that there are no conflicts in frequency assignment?
The Topology Configuration Table.
How does a client locate a wireless local area network (WLAN) when performing passive scanning?
The client listens for beacons until it hears a beacon listing the service set identifier (SSID) of the network it expects to join.
Why has it become cost-effective for enterprise companies to integrate wireless local area network (WLAN) segments into their networks?
The cost of wireless technology has decreased and the quality has increased.
What relationship must be maintained when optimizing cyclic prefix and windowing parameters?
The cyclic prefix sample length must be longer than the roll-off period sample length.
Polarization is defined as which one of the following?
The orientation of an electromagnetic wave's electric field in relationship to the Earth's surface or plane.
In order to route data to best serve all customers, what does configuration of the cable modem termination system (CMTS) depend on?
The physical layout of the network.
What are some measures that can be taken to prevent high voltage standing wave ratios (VSWR) in transmitters and receivers?
Tighten connections between cables and connectors and use impedance-matched hardware throughout.
What DOCSIS 3.1 feature enables an operator to use the same upstream frequency spectrum for DOCSIS 2.0, 3.0, and 3.1?
Time and frequency division multiplexing (TaFDM).
What is the purpose of the Institute of Electrical and Electronics Engineers (IEEE) 802.11 wireless local area network (WLAN) superframe?
To allow fair coexistence between point coordination function (PCF)-mode and distributed coordination function (DCF)-mode clients on the network.
A frame relay network uses a process known as bandwidth-on-demand. Which of the following describes this concept?
When there is data to be sent, the bandwidth is used.
How is a collision detected in carrier sense multiple access with collision detection (CSMA/CD)?
While transmitting, the node listens to the bus, comparing the received frame to what was transmitted. If the received frame is different than what was transmitted, a collision is assumed.
Which operating system (OS) was the first to support the Plug-and-Play standard?
Windows 95.
Residential gateways have been around for quite some time, but what capability was added to connect to Institute of Electrical and Electronics Engineers (IEEE) 802.11b-, 802.11g-, 802.11n-, and 802.11ac-compliant devices?
Wireless capability.
What does a basic service set (BSS) consist of?
A BSS consists of one access point (AP) and one or more wireless clients.
The unit of information used by an asynchronous transfer mode (ATM) network is the:
Cell.
What happens if a sending node wants to transmit data that is longer than the maximum packet size?
The Network Layer splits the data into more than one packet.
In the DOCSIS architecture, what performs the back office tasks that provision, configure, and manage cable modem operations?
The Operational Support Systems (OSS).
What must be understood when placing a DOCSIS 3.1 orthogonal frequency division multiplexing (OFDM) physical link channel (PLC) in the downstream spectrum?
The PLC carries essential information and should be placed in a portion of frequency spectrum that has little noise and minimal ingress and interference.
Which of the following represents the basic definition of a collision domain?
The area of a network where all nodes receive all frames transmitted.
In which of the following applications might a wireless local area network (WLAN) be deployed in a distribution layer role?
As a building-to-building bridge used to link corporate network segments.
The Data Link Layer perceives bits as logical groupings called
Frames.
In what two ways is the gateway used?
As a router and a protocol converter.
How does spread spectrum technology reduce the probability of signal jamming?
By transmitting over a wide frequency spectrum.
What comprises the measurable energy in an orthogonal frequency division multiplexing (OFDM) channel?
The channel's encompassed frequency spectrum minus the unmodulated spectrum in the internal excluded subcarriers and exclusion bands.
You wish to build a wireless network that provides significantly better throughput than a single Institute of Electrical and Electronic Engineers (IEEE) 802.11b access point (AP). Which of the following is an acceptable solution?
Use IEEE 802.11-compliant equipment operating in the 5 gigahertz (GHz) Unlicensed National Information Infrastructure (U-NII) bands, allowing for more more non-overlapping channels.
Which of the following is an advantage of a switched service over a point-to-point service?
Variable capacity is available with switched services.
Which one of the following tasks is the best choice for troubleshooting the near/far problem?
· Review the location of the stations (clients) on the network.
Which one of the following statements describes encapsulation?
A computer adding headers to outbound data.
What is the typical coverage pattern of a semidirectional antenna?
A hemispherical or cylindrical pattern.
Because they use different transmission and coding schemes, the DOCSIS 3.1 Physical (PHY) Layer is incompatible with the PHY Layer of previous DOCSIS versions. How does DOCSIS 3.1 comply with the requirement of compatibility with previous DOCSIS versions?
DOCSIS 3.1 has two PHY Layers, one for previous DOCSIS versions and another for DOCSIS 3.1. Both Layers can operate simultaneously or individually.
In a segmented wireless local area network (WLAN) that has a different Internet protocol (IP) address for each segment, which solution allows mobile clients to maintain their connectivity when roaming into different segments?
Deploying all access points (AP) on a single virtual local area network (VLAN) using a flat IP subnet for all APs so that no change of IP address for roaming clients occurs and all traffic goes through a central controller.
What is used in orthogonal frequency division multiplexing (OFDM) to transform the serial data stream from the time domain to multiple subcarriers in the frequency domain?
Fast Fourier transform (FFT) algorithms compute the discrete Fourier transform (DFT).
Which one of the following radio frequency (RF) behaviors is defined as "the bending of a wave as it passes through a medium of different density"?
Refraction.
In modular cable modem termination system (M-CMTS) architecture, what automatically compensates for cable length and ensures that the M-CMTS clients have the same sense of time and frequency?
The DOCSIS Timing Interface (DTI) server.
What does the term "binary" indicate about a signal?
The signal only has two values representing the digital bits one and zero.
The Federal Communications Commission (FCC) rules regarding power output for frequency-hopping spread spectrum (FHSS) state that a maximum output to the intentional radiator (IR) with 5 megahertz (MHz) of carrier frequency bandwidth must be which one of the following?
125 milliwatts (mW).
A transmitter outputs 100 milliwatts (mW). An antenna cable connects the transmitter to an amplifier, and the power into the amplifier's input measures 50 mW. The amplifier increases the signal to the original transmitter's power level and sends the signal to the antenna. The antenna receives the signal from the amplifier at 75 mW, and then transmits at 150 mW. What is the intentional radiator's (IR) power level in this radio frequency (RF) circuit?
75 mW.
Ethernet's carrier sense multiple access with collision detection (CSMA/CD) method is defined by what Institute of Electronics Engineers (IEEE) standard?
802.3.
In DOCSIS 3.1 Proactive Network Maintenance (PNM), what interacts with other operational support systems (OSS) servers for key information, such as modem locations?
A PNM server.
Which of the following is a characteristic of an asynchronous transfer mode (ATM) cell?
A cell is always the same size.
When the internal workings of a network are unknown to the user, it is commonly called
A cloud.
In a building entrance, incoming telephone company cables are generally terminated in which of the following?
A cross-connect device.
What are two denotations where the term channel can apply?
A frequency range and a physical path.
The central point of a star topology is usually
A hub.
Why are exclusion bands within DOCSIS 3.1 24 MHz orthogonal frequency division multiplexing (OFDM) channels forbidden?
Because the guard bands are 1 MHz and there must be at least 22 MHz or more of contiguous modulated OFDM subcarriers.
How does frequency division multiplexing (FDM) enable multiple signals to share a common medium?
By assigning each signal a specific frequency and bandwidth, or a channel in TV jargon.
The section of a computer that executes the instructions in a program and directs the flow of information within the computer is which of the following?
Central processing unit (CPU).
What security service in an enterprise wireless gateway enables the wireless network administrator to assign levels of service to a particular user?
Class of service (CoS).
Which type of pilot subcarrier can be identified on a spectrum analyzer screen capture of an orthogonal frequency division multiplexing (OFDM) channel?
Continuous pilot subcarriers.
What challenges do Wireless Internet Service Providers (WISP) have to overcome in order to provide "last mile data delivery" to customers?
Distance to access points (AP), rooftop access, lightning, trees, mountains, tower access, and other physical obstacles to connectivity.
Why is the upstream vulnerable to impairments created inside every connected customer premises?
Each modem has access to the upstream in which the transmitted signals from modems are transported over a common path.
Which is often the most convenient place to run vertical cabling in a multistory building?
Elevator shafts.
In DOCSIS 3.1, the cable modem termination system (CMTS) can support up to 16 downstream profiles per orthogonal frequency division multiplexing (OFDM) channel, but the modems support only how many profiles per OFDM channel?
Four active profiles plus one inactive spare profile (4 + 1) per OFDM channel.
Which is a connection-oriented network service that works at the Data Link Layer to carry traffic over virtual circuits?
Frame relay service.
Where does the DOCSIS 3.1 modem gather its downstream channel parameters from when an orthogonal frequency division multiplexing (OFDM) channel is found?
From the Physical Link Channel (PLC) that is within the OFDM channel.
The most complex internetworking device is the:
Gateway.
What is a consideration when mounting a high-gain omnidirectional antenna indoors on the ceiling?
If the ceiling is too high, the coverage area might not reach the floor where the users are located.
Why is the public switched telephone network (PSTN) typically used to connect local area networks (LAN) with a wide area network (WAN)?.
It is prohibitively expensive to install the physical link between LANs and the PSTN is already installed.
Random access memory (RAM) is volatile, which means that
It loses stored data when power is lost.
Which statement describes a passive injector?
It places direct current (DC) voltage onto a CAT-5e cable.
What happens when an active Ethernet switch fails to sense a power over Ethernet (PoE) device on a port?
It switches off the direct current (DC) voltage on that port.
Why is direct sequence spread spectrum (DSSS) the most widely known and the most used of the spread spectrum types?
Its ease of implementation and high data rates.
Under equal network conditions, what advantage does low-density parity-check (LDPC) forward error correction (FEC) coding have over Reed-Solomon (RS) coding?
LDPC is able to correct errors at orders of modulation that are higher than that of RS coding.
What modulation technique does Institute of Electrical and Electronics Engineers (IEEE) wireless local area network (WLAN) standards 802.11a, 802.11n, and 802.11ac use to achieve higher data throughput?
Orthogonal frequency division multiplexing (OFDM).
What were the original downstream channel assignments used on hybrid fiber/coax networks based upon?
Over-the-air TV channel assignments.
Why is the practical data rate of a 256-QAM, 6 MHz wide single carrier channel only about 38 megabits per second (Mbps) when the raw data rate is 42.88 Mbps?
Overhead drops the practical data rate to about 38 Mbps.
Decapsulation means that each layer in the protocol stack does which of the following?
Removes its protocol header and passes the whole message up the protocol stack.
What is the DOCSIS 3.1 data rate capacity when a DOCSIS 3.1 orthogonal frequency division (OFDM) channel is bonded to legacy DOCSIS 3.0 bonded channels?
The DOCSIS 3.1 OFDM channel adds to the capacities of the legacy DOCSIS 3.0 bonded channels.
A switch normally operates at which of the following layers of the Open Systems Interconnection (OSI) Model?
The Data Link Layer.
Which organization regulates the use of wireless local area network (WLAN) devices in the United States?
The Federal Communications Commission (FCC).
Why is the Fresnel zone important to the integrity of the radio frequency (RF) link or path?
The Fresnel zone defines an area around the RF line-of-sight (RF LOS) that can introduce RF signal interference if blocked.
What does the DOCSIS Media Access Control (MAC) Layer use to instruct the cable modem termination system (CMTS) how to route signals internally?
The MAC Domain-Cable Modem-Service Group (MD-CM-SG).
A router normally operates at which layer of the Open Systems Interconnection (OSI) Model?
The Network Layer.
As a subscriber enters a hotspot area, what signals their mobile wireless device of an available Wi-Fi network?
The access point (AP) advertises to the wireless device to enable connection.
Why is shared key authentication considered a security risk in a wireless local area network (WLAN)?
The access point (AP) transmits the challenge text in the clear and receives the same challenge text encrypted with the wired equivalent privacy (WEP) key.
In a client computer, what program is responsible for determining whether a requested resource is local or located across the network?
The client redirection software.
In DOCSIS 3.1 Proactive Network Maintenance (PNM), what serves as the device under test (DUT)?
The hybrid fiber/coax (HFC) network.
What is Equivalent Isotropically Radiated Power (EIRP)?
The power actually radiated by the antenna element.
Which of the following describes how protocol layers work together?
The receiving protocol layer uses the services of the layer below it and provides services to the layer above it.
Which of the following describes the generally accepted function of a broadband network?
Transports multiple concurrent signals on the same physical medium.
What over-the-top (OTT) delivered content could cause the current broadband network data rates to become inadequate?
Ultra-high definition TV (UHDTV) content.
What does DOCSIS 3.1 employ to fully utilize the entire upstream spectrum at maximum capacity while maintaining backward compatibility with DOCSIS 3.0?
Upstream channel bonding and time and frequency division multiplexing (TaFDM).
