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Communications MCQ Set 1

1. What layer in the TCP/IP stack is equivalent to the Transport layer of the OSI model?
a) Application
b) Host to host
c) Internet
d) Network Access

View Answer

Answer: b [Reason:] The four layers of the TCP/IP stack (also called the DoD model) are Application/Process, Host-to-Host, Internet, and Network Access. The Host-to-Host layer is equivalent to the Transport layer of the OSI model.

2. You want to implement a mechanism that automates the IP configuration, including IP address, subnet mask, default gateway, and DNS information. Which protocol will you use to accomplish this?
a) SMTP
b) SNMP
c) DHCP
d) ARP

View Answer

Answer: c [Reason:] Dynamic Host Configuration Protocol (DHCP) is used to provide IP information to hosts on your network. DHCP can provide a lot of information, but the most common is IP address, subnet mask, default gateway, and DNS information.

3. The DoD model (also called the TCP/IP stack) has four layers. Which layer of the DoD model is equivalent to the Network layer of the OSI model?
a) Application
b) Host to host
c) Internet
d) Network Access

View Answer

Answer: c [Reason:] The four layers of the DoD model are Application/Process, Host-to-Host, Internet, and Network Access. The Internet layer is equivalent to the Network layer of the OSI model.

4. Which of the following protocols uses both TCP and UDP?
a) FTP
b) SMTP
c) Telnet
d) DNS

View Answer

Answer: d [Reason:] DNS and some other services work on both TCP and the UDP protocols. DNS uses TCP for zone exchanges between servers and UDP when a client is trying to resolve a hostname to an IP address.

5. Length of Port address in TCP/IP is _________
a) 4bit long
b) 16bit long
c) 32bit long
d) 8 bit long

View Answer

Answer: b [Reason:] TCP and UDP port numbers are 16 bits in length. So, valid port numbers can theoretically take on values from 0 to 65,535. These values are divided into ranges for different purposes, with certain ports reserved for particular uses.

6. TCP/IP layer is equivalent to combined Session, Presentation and ______
a) Network layer
b) Application layer
c) Transport layer
d) Physical layer

View Answer

Answer: b [Reason:] TCP/IP network model is a hierarchical protocol made up of interactive modules, each of which provides a specific functionality; however, the modules are not necessarily interdependent. It is equivalent to combined session, presentation and application layer.

7. How many levels of addressing is provided in TCP/IP protocol?
a) One
b) Two
c) Three
d) Four

View Answer

Answer: d [Reason:] Four levels of addresses are used in an internet employing the TCP/IP protocols. They are physical (link) addresses, logical (IP) addresses, port addresses, and specific addresses.

8. Virtual terminal protocol is an example of _______
a) Network layer
b) Application layer
c) Transport layer
d) Physical layer

View Answer

Answer: b [Reason:] In open systems, a virtual terminal (VT) is an application service. It allows host terminals on a multi-user network to interact with other hosts regardless of terminal type and characteristics.

9. TCP/IP is related to _______
a) ARPANET
b) OSI
c) DECNET
d) ALOHA

View Answer

Answer: a [Reason:] In 1983, TCP/IP protocols replaced NCP (Network Control Program) as the ARPANET’s principal protocol. And ARPANET then became one component of the early Internet. The starting point for host-to-host communication on the ARPANET in 1969 was the 1822 protocol, which defined the transmission of messages to an IMP.

10. A device operating at network layer is called ____
a) Router
b) Equalizer
c) Bridge
d) Repeater

View Answer

Answer: a [Reason:] A router is a networking device that forwards data packets between computer networks. Routers perform the traffic directing functions on the Internet. It supports different network layer transmission standards. Each network interface is used to enable data packets to be forwarded from one transmission system to another.

11. A device operating at network layer is called ____
a) Router
b) Equalizer
c) Bridge
d) Repeater

View Answer

Answer: d [Reason:] A repeater connects two segments of your network cable. It retimes and regenerates the signals to proper amplitudes and sends them to the other segments. Repeaters work only at the physical layer of the OSI network model.

Communications MCQ Set 2

1. A packet in Transmission Control Protocol (TCP) is called a ______
a) Transmittable slots
b) Packet
c) Segment
d) Source Slots

View Answer

Answer: c [Reason:] Applications working at the Application Layer transfers a contiguous stream of bytes to the bottom layers. It is the duty of TCP to pack this byte stream to packets, known as TCP segments, which are passed to the IP layer for transmission to the destination device.

2. Cable TV and DSL are examples of ________
a) Interconnection of network
b) LAN
c) MAN
d) WAN

View Answer

Answer: c [Reason:] A MAN often acts as a high speed network to allow sharing of regional resources. It typically covers an area of between 5 and 50 km diameter. Examples of MAN are telephone company network that provides a high speed DSL to customers and cable TV network.

3. Station on a wireless ALOHA network is maximum of ________
a) 400 Km
b) 500 Km
c) 600 Km
d) 700 Km

View Answer

Answer: c [Reason:] The stations on a wireless ALOHA networks are a maximum of 600 km apart. It was designed for a radio (wireless) LAN, but it can be used on any shared medium. It is obvious that there are potential collisions in this arrangement. The medium is shared between the stations.

4. IEEE 802.11 defines basic service set as building block of a wireless _____
a) LAN
b) WAN protocol
c) MAN
d) ALOHA

View Answer

Answer: a [Reason:] The IEEE 802.11 topology consists of components interacting to provide a wireless LAN. It enables station mobility transparent to higher protocol layers, such as the LLC.

5. In wireless LAN, there are many hidden stations so that _______ cannot be detected.
a) Frames
b) Collision
c) Signal
d) Data

View Answer

Answer: b [Reason:] In wireless networking, the hidden node problem or hidden terminal problem occurs when a node is visible from a wireless access point (AP), but not from other nodes communicating with said AP. This leads to difficulties in media access control and collisions could not be detected.

6. A set that makes stationary or mobile wireless station and also have optional central base station is known as _______
a) Basic service set
b) Extended service set
c) Network point set
d) Access point

View Answer

Answer: a [Reason:] A set that makes stationary or mobile wireless station and also have optional central base station is known as basic service set. BSS is made of stationary or mobile wireless stations and an optional central base station, known as the access point (AP).

7. Wireless communication started in _____
a) 1869
b) 1895
c) 1879
d) 1885

View Answer

Answer: b [Reason:] In England, Guglielmo Marconi began his wireless experiments in 1895. On 2 June 1896, he filed his provisional specification of a patent for wireless telegraphy. He demonstrated the system to the British Post Office in July.

8. Wireless transmission is divided into ______
a) 3 broad groups
b) 6 broad groups
c) 9 broad groups
d) 8 broad groups

View Answer

Answer: a [Reason:] We can divide wireless transmission into three broad groups: radio waves, microwaves, and infrared waves. Radio waves are used for multicast communications, such as AM and FM radio, television, maritime radio, cordless phones and paging systems. Microwave propagation is line-of-sight.

9. Transmission Control Protocol/Internet Networking Protocol have ________
a) Four Layers
b) Five Layers
c) Six Layers
d) Seven Layers

View Answer

Answer: a [Reason:] TCP/IP functionality is divided into four layers, each with its own set of agreed-upon protocols: The datalink layer consists of methods and protocols that operate only on a link. The Internet layer connects independent networks to transport the packets. The Transport layer handles communications between. The Application layer standardizes data exchange for applications.

10. Packets of data that is transported by IP is called _______
a) Datagrams
b) Frames
c) Segments
d) Encapsulate message

View Answer

Answer: a [Reason:] The format of data that can be recognized by IP is called an IP datagram. It consists of two components, the header and data, which need to be transmitted. The fields in the datagram, except the data, have specific roles to perform in the transmission of data.

11. Parameter that is normally achieved through a trailer added to end of frame is ________
a) Access Control
b) Flow Control
c) Error Control
d) Physical addressing

View Answer

Answer: c [Reason:] The data link layer adds reliability to the physical layer by adding mechanisms to detect and retransmit damaged or lost frames. It also uses a mechanism to recognize duplicate frames. Error control is normally achieved through a trailer added to the end of the frame.

Communications MCQ Set 3

1. Which of the following is not a statistical models for multipath fading channels?
a) Clarke’s model for flat fading
b) Saleh and Valenzuela indoor statistical model
c) Two ray Rayleigh fading model
d) Faraday model

View Answer

Answer: d [Reason:] Several multipath models have been suggested to explain the observed statistical nature of a mobile channel. Clarke’s model for flat fading, Saleh and Valenzuela indoor statistical model, two ray Rayleigh fading model are some of the statistical model for multipath fading channels.

2. Who presented the first statistical model for multipath fading channel?
a) Ossana
b) Rayleigh
c) Newton
d) Faraday

View Answer

Answer: a [Reason:] The first statistical model was presented by Ossana. It was based on interference of wave incident and reflected from the flat sides of randomly located buildings. Ossana model predicts flat fading power spectra that were in agreement with measurements in suburban areas.

3. Clarke’s model assumes a horizontal polarized antenna. State whether True or False.
a) True
b) False

View Answer

Answer: b [Reason:] Clarke developed a model where the statistical characteristics of the electromagnetic fields of the received signal at the mobile are deduced from scattering. Clarke’s model assumes a fixed transmitter with a vertically polarized antenna.

4. A wave that is incident on mobile does not undergo Doppler shift. State whether True or False.
a) True
b) False

View Answer

Answer: b [Reason:] Every wave that is incident on the mobile undergoes a Doppler shift. It is due to the motion of the receiver and it arrives at the receiver at the same time. Therefore, there is no excess delay due to multipath for any of the waves.

5. Which of the following is an important statistics of a Rayleigh fading useful for designing error control codes and diversity schemes?
a) Mobile speed
b) Doppler frequency
c) Level crossing rate (LCR)
d) Power density

View Answer

Answer: c [Reason:] The level crossing rate (LCR) and average fade duration of a Rayleigh fading signal are important statistics. They are useful for designing error control codes and diversity schemes to be used in mobile communication.

6. The level crossing rate (LCR) is defined as expected rate at which _______ fading envelope crosses a specified level.
a) Rayleigh
b) Saleh
c) Vanezuela
d) Faraday

View Answer

Answer: a [Reason:] The LCR is defined as the expected rate at which the Rayleigh fading envelop is normalized to the local rms signal level. And it crosses a specified level in a positive going direction.

7. Level crossing rate is a function of _______
a) Power transmitted by base station
b) Power density of receiver
c) Mobile speed
d) Bit error rate

View Answer

Answer: c [Reason:] The level crossing rate is a function of mobile speed. Because, it is possible to relate the time rate of change of the received signal of the signal level and velocity of the mobile.

8. Clarke’s model considers the multipath time delay. State whether True or False.
a) True
b) False

View Answer

Answer: b [Reason:] Clarke’s model and the statistics for Rayleigh fading are for flat fading conditions. They do not consider multipath time delay.

9. Saleh and Venezuela reported the results of ______ propagation measurements.
a) Indoor
b) Outdoor
c) Air
d) High frequency

View Answer

Answer: a [Reason:] Saleh and Venezuela reported the results of indoor propagation measurements. The measurements were made between two vertically polarized omnidirectional antennas located on the same floor of a medium sized office building.

10. Saleh and Venezuela show that indoor channel is _______ time varying.
a) Not
b) Very slow
c) Fast
d) Very fast

View Answer

Answer: b [Reason:] The results obtained by Saleh and Venezuela shows that the indoor channel is quasi static or very slow time varying. It shows that the statistics of the channel impulse response are independent of transmitting and receiving antenna polarization.

11. What is the full form of SIRCIM?
a) Simulation of Indoor Radio Channel Impulse response Model
b) Statistical Indoor Radio Channel for Impulse Model
c) Statistical Impulse Radio Channel for Indoor Model
d) Simulation of Impulse Radio Channel for Indoor Model

View Answer

Answer: a [Reason:] SIRCIM stands for Simulation of Indoor Radio Channel Impulse response Model. SIRCIM generates realistic samples of small scale indoor channel impulse response measurements.

Communications MCQ Set 4

1. Which of the following is not a characteristic of 3G network?
a) Communication over VoIP
b) Unparalleled network capacity
c) Multi-megabit Internet access
d) LTE based network

View Answer

Answer: d [Reason:] Multi-megabit Internet access, communication using Voice over internet Protocol (VoIP), voice activated calls, unparalleled network capacity are some of the characteristics of 3G network. 3G systems promise unparalleled wireless access which is not possible in 2G systems. LTE (Long term Evolution) is a standard of 4G systems.

2. What is the term used by ITU for a set of global standards of 3G systems?
a) IMT 2000
b) GSM
c) CDMA
d) EDGE

View Answer

Answer: a [Reason:] International Telecommunications Union (ITU) used the term IMT-2000 in 1998. It is used for a set of global standards for third generation (3G) mobile telecoms services and equipment.

3. Which of the following leads to evolution of 3G networks in CDMA systems?
a) IS-95
b) IS-95B
c) CdmaOne
d) Cdma2000

View Answer

Answer: d [Reason:] 3G evolution of CDMA system leads to cdma2000. It is based on the fundamentals of IS-95 and IS-95B. IS-95 is a 2G standard for CDMA systems. IS-95B is a CDMA system for 2.5G networks.

4. Which of the following leads to the 3G evolution of GSM, IS-136 and PDC systems?
a) W-CDMA
b) GPRS
c) EDGE
d) HSCSD

View Answer

Answer: a [Reason:] The 3G evolution for GSM, IS-136 and PDC systems leads to W-CDMA (Wideband CDMA). It is based on the network fundamentals of GSM, as well as merged versions of GSM and IS-136 through EDGE. GPRS, EDGE and HSCSD are 2.5G networks.

5. What is 3GPP?
a) Project based on W-CDMA
b) Project based on cdma2000
c) Project based on 2G standards
d) Project based on 2.5G standards

View Answer

Answer: a [Reason:] 3GPP is a 3G Partnership Project for Wideband CDMA standards based on backward compatibility with GSM and IS-136. The project was established in December, 1998. Its initial scope was to make a globally applicable third generation mobile phone system.

6. What is 3GPP2?
a) Project based on W-CDMA
b) Project based on cdma2000
c) Project based on 2G standards
d) Project based on 2.5G standards

View Answer

Answer: b [Reason:] 3GPP2 is a 3G Partnership Project for Cdma2000 standards based on backward compatibility with earlier CdmaOne 2G CDMA technology. It was initiated by IMT-2000 to cover high speed, broadband and Internet Protocol (IP) based mobile systems. It mainly focuses on North American and Asian regions.

7. Which of the following is not a standard of 3G?
a) UMTS
b) Cdma2000
c) TD-SCDMA
d) LTE

View Answer

Answer: d [Reason:] UMTS (Universal Mobile Telecommunication System), TD-SCDMA (Time Division Synchronous Code Division Multiple Access), Cdma2000 are the standards defined for 3G networks. LTE (Long Term Evolution) is a 4G standard for high speed wireless communication.

8. Which of the following 3G standard is used in Japan?
a) Cdma2000
b) TD-SCDMA
c) UMTS
d) UTRA

View Answer

Answer: c [Reason:] Japan uses UMTS (W-CDMA) standard for its 3G network. The standards used are UMTS 800, UMTS 900, UMTS 1500, UMTS 1700 and UMTS 2100. They are standardized by ARIB (Association of Radio industries and Business).

9. What does the number 2000 in IMT-2000 signifies?
a) Year
b) Number of subscribers per cell
c) Number of cells
d) Area (Km)

View Answer

Answer: a [Reason:] The International Telecommunication Union (ITU) defined the third generation (3G) of mobile telephony standards, IMT-2000 to facilitate growth, increase bandwidth, and support more diverse applications. The number 2000 in IMT-2000 indicates the start of the system (year 2000) and the spectrum used (around 2000 MHz).

10. Which of the following is not an application of third generation network?
a) Global Positioning System (GPS)
b) Video conferencing
c) Mobile TV
d) Downloading rate upto 1 Gbps

View Answer

Answer: d [Reason:] 3G applications include GPS (Global Positioning System), MMS (Multimedia Messaging System), video conferencing, location based services, video on demand, wireless voice telephony and high data rates with peak downloading rate of 100 Mbps. For 4G networks, the peak downloading rate is 1 Gbps.

Communications MCQ Set 5

1. TDMA systems transmit in a continuous way.
a) True
b) False

View Answer

Answer: b [Reason:] TDMA systems transmit data in a buffer and burst method. Thus, the transmission for any user is not continuous.

2. Preamble contains _____
a) Address
b) Data
c) Guard bits
d) Trail bits

View Answer

Answer: a [Reason:] TDMA frame is made up of a preamble, an information message and the trail bits. In a TDMA frame, the preamble contains the address and synchronization information that both the base station and the subscribers use to identify each other.

3. _____ are utilized to allow synchronization of the receivers between different slots and frames.
a) Preamble
b) Data
c) Guard bits
d) Trail bits

View Answer

Answer: c [Reason:] Guard times are utilized to allow synchronization of the receivers between different slots and frames. TDMA/FDD systems intentionally induce several time slots of delay between the forward and reverse time slots for a particular user.

4. Which of the following is not true for TDMA?
a) Single carrier frequency for single user
b) Discontinuous data transmission
c) No requirement of duplexers
d) High transmission rates

View Answer

Answer: a [Reason:] TDMA share a single carrier frequency with several users, where each user makes use of non-overlapping time slots. The number of time slots per frame depends on several factors, such as modulation technique, available bandwidth etc.

5. Because of _______ transmissions in TDMA, the handoff process in _____
a) Continuous, complex
b) Continuous, simple
c) Discontinuous, complex
d) Discontinuous, simple

View Answer

Answer: d [Reason:] Because of discontinuous transmissions in TDMA, the handoff process is much simpler for a subscriber unit, since it is able to listen for other base stations during idle time slots.

6. _____ synchronization overhead is required in TDMA due to _______ transmission.
a) High, burst
b) High, continuous
c) Low, burst
d) No, burst

View Answer

Answer: a [Reason:] High synchronization overhead is required in TDMA systems because of burst transmissions. TDMA transmissions are slotted, and this requires the receivers to be synchronized for each data burst.

7. TDMA allocates a single time per frame to different users.
a) True
b) False

View Answer

Answer: b [Reason:] TDMA has an advantage that it can allocate different numbers of time slots per frame to different users. Thus, bandwidth can be supplied on demand to different users by concatenating or reassigning time slots based on priority.

8. ______ of TDMA system is a measure of the percentage of transmitted data that contains information as opposed to providing overhead for the access scheme.
a) Efficiency
b) Figure of merit
c) Signal to noise ratio
d) Mean

View Answer

Answer: a [Reason:] Efficiency of TDMA system is a measure of the percentage of transmitted data that contains information as opposed to providing overhead for the access scheme. The frame efficiency is the percentage of bits per frame which contain transmitted data.

9. A TDMA system uses 25 MHz for the forward link, which is broken into radio channels of 200 kHz. If 8 speech channels are supported on a single radio channel, how many simultaneous users can be accommodated?
a) 25
b) 200
c) 1600
d) 1000

View Answer

Answer: d [Reason:] For a TDMA system that uses 25 MHz for the forward link, which is broken into radio channels of 200 kHz. If 8 speech channels are supported on a single radio channel, 1000 simultaneous users can be accommodated as N=(25 MHz)/(200 kHz/8).

10. What is the time duration of a bit if data is transmitted at 270.833 kbps in the channel?
a) 270.833 s
b) 3 μs
c) 3.692 μs
d) 3.692 s

View Answer

Answer: c [Reason:] If data is transmitted at 270.833 kbps in the channel, the time duration of a bit will be 3.692 μs, as Tb=(1/270.833 kbps)= 3.692 μs.