APPLES 2 Flashcards
The technique of temporarily delaying outgoing acknowledgements so that they can be hooked onto the next outgoing data frame is called______.
a. parity check
b. fletcher’s checksum
c. piggybacking
d. cyclic redundancy check
c. piggybacking
What are the services provided by layer 2 of the 0SI reference model?
a. All of these
b. Physical Addressing and Error Control
c. Flow Control
d. Framing and Access Control
a. All of these
Name the Byte oriented protocols commonly used?
a. BISYNC, BISYNC and HDLC
b. SONET, BISYNC, PPP and HDCL
c. None of these
d. DDCMP, BISYNC and PPP
d. DDCMP, BISYNC and PPP
Unauthorised access of information from a wireless device through a bluetooth connection is called ________.
a. bluemaking
b. bluescoping
c. bluesnarfing
d. bluestring
c. bluesnarfing
Error detection technques are used in data communications. What are they?
a. Checksum
b. CRC
c. All of these
d. VRC and LRC
c. All of these
CSMA/CD is not suitable for a high propagation delay network like satellite network?
a. True
b. False
a. True
The maximum size of payload field in Ethernet frame is __________.
a. 1300 bytes
b. 1200 bytes
c. 1000 bytes
d. 1500 bytes
d. 1500 bytes
Determine the maximum length of the cable in km, for transmitting data at a rate of 500 Mbps in an Ethernet LAN with frames of size 10, 000 bits. Assume the signal speed in the cable to be 2x10^5 km/s?
a. none of these
b. 4
c. 3
d. 2
d. 2
Which multiple access technique is used by IEEE 802.11 standard for wireless LAN?
a. CSMA/CD
b. CSMA/CA
c. ALOHA
d. CDMA
b. CSMA/CA
Describe the performance of LRC in data communications?
a. LRC increases the probability of detecting burst errors.
b. LRC error checker will not detect errors if two bits in one data units are damaged.
c. All of these
d. LRC error checker will not detect errors if two bits in exactly the same position in another data unit are damaged.
c. All of these
What are the two main types of framing in layer 2 of the OSI model?
a. Fixed length framing
b. Variable length framing
c. Fixed size framing
d. Variable size framing
Fixed size framing and
Variable size framing
A network with CSMA/CD protocol in the MAC layer is running at 1Gbps over a 1 km cable with no repeaters. The signal speed in the cable is 2x10^8 m/sec. What would be the minimum frame size for this network?
a. 1.25kB
b. 1.30kB
c. 1.50kB
d. 1.45kB
a. 1.25kB
Which of the following is the multiple access protocol for channel access control?
a. Both CSMA/CD & CSMA/CA
b. CSMA/CD
c. CSMA/CA
d. HDLC
a. Both CSMA/CD & CSMA/CA
Which of the following best describes CSMA protocol?
a. None of the these
b. sense before transmit
c. Act before you talk
d. Listen before transmit
b. sense before transmit
The physical layer is responsible for?
a. all of these
b. line coding
c. modulation
d. channel coding
a. all of these
What are the two primary functions of the MAC sublayer?
a. LLC Sublayer
b. Both MAC and LLC layers
c. DLC sublayer
d. MAC sublayer
d. MAC sublayer
Header of a frame generally contains ____________
a. frame identifier
b. addresses
c. all of the mentioned
d. synchronization bytes
c. all of the mentioned
Which sub-layer of the data link layer performs data link functions that depend upon the type of medium?
a. network interface control sub-layer
b. logical link control sub-layer
c. media access control sub-layer
d. error control sub-layer
c. media access control sub-layer
The strategy of doubling the delay interval between each retransmission attempt is known as?
a. Exponential Timeoff
b. None of these
c. Exponential Backoff
d. Exponential delay
c. Exponential Backoff
Consider the data unit 10011001111000100010010010000100 to be transmitted by the sender. Determine the following,
a) number of blocks after segmenting the message?
b) number of bits per block?
c) The checksum?
a) 4
b) 8
c) 11111110
Which IEEE standard is used for Ethernet?
IEEE 802.3
What are the different types of STP ports?
a. Root port, Designated port and Forwarding port
b. Root port, Designated port, Forwarding port, Blocked port
c. Root port, Designated port and Blocked port
d. None of these
b. Root port, Designated port, Forwarding port, Blocked port
What is the purpose of Spanning Tree Protocol in a switched LAN?
a. To prevent switching loops in networks with redundant switched paths
b. To manage the VLAN database across multiple switches
c. To prevent routing loops in networks with redundant paths
d. To provide a mechanism for network monitoring in switched environments
a. To prevent switching loops in networks with redundant switched paths
The sharing of a medium and its link by two or more devices is called _________
a. Microplexing
b. Multiplexing
c. Fully duplexing
d. Duplexing
b. Multiplexing
Which transmission media has the highest transmission speed in a network?
a. optical fiber
b. coaxial cable
c. twisted pair cable
d. electrical cable
a. optical fiber
Time it takes to place the complete data packet on the transmission medium for processing is referred to as?
a. Queuing delay
b. Propagation delay
c. Transmission delay
d. Processing delay
c. Transmission delay
Which IEEE standard is used for WiFi?
IEEE 802.11
Which IEEE standard is used for Bluetooth?
IEEE 802.15
When 2 or more bits in a data unit has been changed during the transmission, the error is called ____________
a. burst error
b. double error
c. inverted error
d. random error
a. burst error
Wireless transmission can be done via
a. microwaves
b. radio waves
c. infrared
d. all of these
d. all of these
Bits can be send over guided and unguided media as analog signal by
a. amplitude modulation
b. phase modulation
c. frequency modulation
d. digital modulation
d. digital modulation
For the IEEE 802.11 MAC protocol for wireless communication, which of the following statements is TRUE?
i. At least three non-overlapping channels are available for transmissions.
ii. The RTS-CTS mechanism is used for collision detection.
iii. Unicast frames are ACKed
I and III only
Give an example of clock based framing?
a. DDCMP
b. SONET
c. PPP
d. BISYNC
b. SONET
Give the sublayer that is responsible for flow control?
a. LLC Sublayer
b. MAC sublayer
c. Both DLC or LLC
d. DLC sublayer
c. Both DLC or LLC
Multiplexing is used in _______
a. Packet & Circuit switching
b. Circuit switching
c. Packet switching
d. Data switching
b. Circuit switching
In wireless distribution system __________
a. multiple access point are inter-connected with each other
b. access points are not required
c. only one access point exists
d. there is no access point
a. multiple access point are inter-connected with each other
An interconnected collection of piconet is called ___________
a. multinet
b. micronet
c. mininet
d. scatternet
d. scatternet
What are the main ways of addressing transmission errors in framing?
a. Character stuffing
b. Bit stuffing
c. None of these
d. Byte stuffing
Bit stuffing and Character stuffing
In flow control, station A uses 32 byte packets to transmit message to station B using a sliding window protocol. The round trip delay between A and B is 85 milliseconds and bottleneck bandwidth on the path between A and B is 160kbps. Determine the Bandwidth Delay product (BDP) and determine the optimal window size that A should use?
a. BDP 1.8kB, Optimal window size 74.5B
b. BDP 1.7kB, Optimal window size 54.4B
c. BDP 1.8kB, Optimal window size 64.5B
d. BDP 1.9kB, Optimal window size 54.9B
b. BDP 1.7kB, Optimal window size 54.4B
Which of the following best describes the operation of the spanning tree protocol in computer networks?
a. STP picks one path to forward frames and blocks to other redundant links and when blocking happens then Loops are prevented
b. STP compute the redundant links to root bridge
c. STP select a reference point known as the Root Bridge
d. All of these
d. All of these
Ethernet frame consists of ____________
a. Default mask
b. MAC address
c. IP address
d. Network address
b. MAC address
What is the primary purpose of a VLAN?
a. To create a virtual private network
b. Demonstrating the proper layout for a network
c. Segmenting a network inside a switch or device
d. Simulating a network
c. Segmenting a network inside a switch or device
The message 11001001 at the sender side is to be transmitted using CRC polynomial x^3+1 to protect it from errors. Determine the following?
a) the bits of the divisor L?
b) the length of the CRC bits to be appended to the message?
c) The CRC bits
d) Message to be transmitted?
a) 1001
b) 3
c) 011
d) 11001001011
Frame format include the header Network layer PDU and Trailer.
a. True
b. False
a. True
Using the principle of binary to hexadecimal conversion, convert 5B base 16 to binary.
0101 1011
The physical layer concerns with
a. none of these
b. application to application delivery
c. process to process delivery
d. bit-by-bit delivery
d. bit-by-bit delivery
What is the access point (AP) in a wireless LAN?
a. all the nodes in the network
b. both device that allows wireless devices to connect to a wired network and wireless devices itself
c. device that allows wireless devices to connect to a wired network
d. wireless devices itself
c. device that allows wireless devices to connect to a wired network
What is Start Frame Delimiter (SFD) in Ethernet frame?
a. 11111111
b. 10101010
c. 10101011
d. 00000000
c. 10101011
In framing, Bits flow between adaptors and frames flow between hosts.
a. True
b. False
a. True
Which of the following is a data link protocol?
a. Ethernet
b. HDLC
c. All of the mentioned
d. PPP
c. All of the mentioned
Bluetooth is the wireless technology for __________
a. local area network
b. personal area network
c. metropolitan area network
d. wide area network
b. personal area network
Framing can be broadly categorised in TWO. What are these categories?
Bit and Byte Oriented approaches
What is the destination MAC address used by Bridge Protocol Data Units(BPDUs)?
a. 02-80-c2-00-00-02
b. none of these
c. 00-80-c2-00-00-01
d. 01-80-c2-00-00-00
d. 01-80-c2-00-00-00
Determine the LRC given the data blocks 11100111 00111001 00111001 10101001 and find the data portion that is transmitted?
LRC 10101010 and Data 10101001 00111001 00111001 11100111
Physical layer provides
a. electrical specification of transmission line signal level
b. specification for IR over optical fibre
c. all of these
d. mechanical specifications of electrical connectors and cables
c. all of these
Propagation delay depends on ___________
a. Distance between routers
b. Speed of the CPU
c. Packet length
d. Transmission rate
a. Distance between routers
Determine the type of the following destination addresses?
a) 4A:30:10:21:10:1A
b) 47:20:1B:2D:08:1E
c) FF:FF:FF:FF:FF:FF
a) Unicast
b) multicast
c) broadcast
Station A needs to send a message consisting of 9 packets to station B using sliding window (window size 3) and go-back-n ARQ error control strategy. All packet are ready and immediately available for transmission. If every 5th packet that A transmits gets lost (but no ACKs from B ever get lost), then what is the number of packets that A will transmit for sending the message to B?
a. 17
b. 16
c. 14
d. 15
b. 16
Which of the following delay is faced by the packet in travelling from one end system to another?
a. Propagation delay
b. Queuing delay
c. Transmission delay
d. All of the mentioned
d. All of the mentioned
Which IEEE standard is used for Logical Link Control sublayer of the data link?
802.15
Describe the checksum operation at the receiver side?
a. Collect all data blocks excluding the checksum, XOR all the data blocks and checksum, if the result if all 1’s, ACCEPT; Else REJECT
b. None of the these
c. Collect all data blocks including the checksum, divide all the data blocks and checksum, if the result if all 0’s, ACCEPT; Else REJECT
d. Collect all data blocks including the checksum, sum all the data blocks and checksum, if the result if all 1’s, ACCEPT; Else REJECT.
d. Collect all data blocks including the checksum, sum all the data blocks and checksum, if the result if all 1’s, ACCEPT; Else REJECT.
If the time it takes for station A to transmit a signal to B is 10ms and B acknowledges the transmission within the same medium. What will be the round trip time?
a. 40ms
b. 30ms
c. 20ms
d. 10ms
d. 20ms
The data link layer takes the packets from _________ and encapsulates them into frames for transmission.
a. application layer
b. transport layer
c. network layer
d. physical layer
c. network layer
Given the frame transmission time TFr to be 100ms. What is the vulnerable time in which collision may occur in Pure ALOHA compared to slotted ALOHA?
a. 200ms for Pure ALOHA and 200ms for Slotted ALOHA
b. none of these
c. 200ms for Pure ALOHA and 100ms for Slotted ALOHA
d. 100ms for Pure ALOHA and 200ms for Slotted ALOHA
c. 200ms for Pure ALOHA and 100ms for Slotted ALOHA
Which of the following tasks is not done by data link layer?
a. error control
b. flow control
c. encoding
d. framing
c. encoding
What is the hexadecimal equivalent of the following Ethernet address?
01011010 00010001 01010101 00011000 10101010 00001111
a. 4B-20-1B-2D-08-1E
b. 4A-30-10-21-10-1A
c. 5A-11-55-18-AA-0F
d. 5A-20-1B-1D-08-1E
c. 5A-11-55-18-AA-0F
When node A wishes to transmit a frame to node B, it does not inform its adaptor to transmit a frame from the node’s memory.
a. True
b. False
b. False
At what sublayer of layer 2 does WiFi apply?
a. DLC sublayer
b. Both MAC and LLC layers
c. LLC Sublayer
d. MAC sublayer
d. MAC sublayer
The portion of physical layer that interfaces with the media access control sublayer is called?
a. physical data sublayer
b. physical address sublayer
c. none of these
d. physical signalling sublayer
d. physical signalling sublayer
The physical layer translates logical communication requests from the ______ into hardware specific operations.
a. transport layer
b. application layer
c. data link layer
d. network layer
c. data link layer
Transmission delay does not depend on _____________?
a. Packet length
b. Distance between routers
c. Transmission rate
d. Bandwidth of medium
b. Distance between routers
In asynchronous serial communication the physical layer provides
a. both (a) and (b)
b. flow control
c. start and stop signalling
d. none of these
a. both (a) and (b)
An ethernet frame that is less than the IEEE 802.3 minimum length of 64 octets is called _______
a. short frame
b. runt frame
c. man frame
d. mini frame
b. runt frame
What is the propagation time if the distance between node A and B is 12000km. Assume the propagation speed to be 2.4x10^8 m/s in the media cable used?
50ms
An Ethernet MAC sublayer receives 40 bytes of data from the upper layer. How many bytes of padding must be added to the data?
6 Bytes
