Data Communication and Computer Networks 01

1. The technique of temporarily delaying outgoing acknowledgements so that they can be hooked onto the next outgoing data frame is known as                                                         [Paper III December 2012]
(A) Bit stuffing
(B) Piggy backing
(C) Pipelining
(D) Broadcasting
10. Match the following:                                                                          [Paper III December 2012]
     List – I         List – II 
a. Application layer 1. TCP
b. Transport layer 2. HDLC
c. Network layer 3. HTTP
d. Data link layer 4. BGP
Codes:
        a b c d
(A) 2 1 4 3
(B) 3 4 1 2
(C) 3 1 4 2
(D) 2 4 1 3

2. In classfull addressing, an IP address 123.23.156.4 belongs to ______ class format.
  [Paper III December 2012]
(A) A
(B) B
(C) C
(D) D

3. Which are the classifications of data used in Mobile Applications? [Paper III December 2012]
(A) Private data, User data, Shared data.
(B) Public data, User data, Virtual data.
(C) Private data, Public data, Shared data.
(D) Public data, Virtual data, User data.

4. Match the following with respect to the Mobile Computing Architecture [Paper III December 2012]
a. Downlink control                                     1. 100 Mbps
b. Radio communication data rate                  2. Residency latency (RL)
c. The average duration of user’s stay in cell 3. Sending data from a BS to MD
d. FDDI bandwidth                                     4. 2-Mbps
Codes :
        a b c d
(A) 2 1 4 3
(B) 3 4 2 1
(C) 4 1 2 1
(D) 4 3 1 2

5. Hub is a term used with                                                                [Paper II December 2011]

(A) A Star Networks

(B) A Ring Networks

(C) A Router

(D) A Bridge

6. Which of the following network access standard disassembler is used for connection station to a packet switched network?                                                                           [Paper II December 2011]

(A) X.3            (B) X.21

(C) X.25          (D) X.75

7. A station in a network in a network forward incoming packets by placing them on its shortest output queue. What routing algorithm is being used?                                    [Paper II December 2011]

(A) Hot potato routing

(B) Flooding

(C) Static routing

(D) Delta routing

8. Start and stop bits are used in serial communications for                [Paper II December 2011]

(A) Error detection

(B) Error correction

(C) Synchronization

(D) Slowing down the communication

9. Handoff is the mechanism that                                                       [Paper II December 2011]

(A) transfer an ongoing call from one base station to another

(B) initiating a new call

(C) dropping an ongoing call

(D) none of above

10. The number of bits required for an IPV6 address is                      [Paper II December 2011]

(A) 16              (B) 32

(C) 64              (D) 128

SOLUTIONS

1. B

Whenever a receiver is about to ACK the data it has received from the client, it does not immediately, rather it delays the ACK and see whether any data has to be sent to the client, so the ACK can be sent along with the data. This is called Piggy backing.

2. A
Class A Ranges from 0.0.0.0 to 127.255.255.255

3. C

4. B

5. A

6. A

X.3 is an ITU-T standard indicating what functions are to be performed by a Packet Assembler/Disassembler (PAD) when connecting character-mode data terminal equipment (DTE), such as a computer terminal, to a packet switched network such as an X.25 network, and specifying the parameters that control this operation

X.21 (sometimes referred to as X21) is an interface specification for differential communications introduced by the ITU-T. X.21 was first introduced as a means to provide a digital signalling interface for telecommunications between carriers and customers' equipment.

X.25 is an ITU-T standard protocol suite for packet switched wide area network (WAN) communication. An X.25 WAN consists of packet-switching exchange (PSE) nodes as the networking hardware, and leased lines, plain old telephone service connections or ISDN connections as physical links. While X.25 has been, to a large extent, replaced by less complex protocols, especially the Internet protocol (IP), the service is still used and available in niche and legacy applications.

X.75 is an International Telecommunication Union (ITU) standard specifying the interface for interconnecting two X.25 networks. X.75 is almost identical to X.25. The significant difference is that while X.25 specifies the interface between a subscriber (Data Terminal Equipment (DTE)) and the network (Data Circuit-terminating Equipment (DCE)), X.75 specifies the interface between two networks (Signalling Terminal Equipment (STE))

7. A

Hot potato routing is a routing technique enabling packet routing without storing them in buffers. The hot potato routing technique continuously transfers data packets until reaching their destination without the packets having to wait or being stored in a buffer. Any router configured for hot potato will immediately route the packet upon receiving it. Unlike other routing techniques, where the packets compete for the best path to the destination node having to wait if it's not available, hot potato routes packets whenever it receives them, regardless of whether the primary and optimal transmission route is available or not. So it naturally uses the path with shortest output queue.

A flooding algorithm is an algorithm for distributing material to every part of a connected network. The packet received is forwarded through all interfaces except the one on which it arrived.

Routing can be broadly classified into two: static and dynamic, are based on the way in which the routing tables are updated every time they are used. The routers in which the data is stored and updated manually are called static routers. On the other hand, the routing in which the information is changed dynamically, by the router itself, is referred to as dynamic routing.

In Delta routing each node calculates the cost of each line (that is some functions of the delay, queue length, utilization and bandwidth etc.)  and from time to time sends a packet to the central node giving it these values which then calculates the k best paths from node.

8. C

9. A

10. D

IPv6 uses a 128-bit address, allowing 2¹²⁸, or approximately 3.4×10³⁸ addresses. IPv6 addresses are represented as eight groups of four hexadecimal digits separated by colons.