Download DU (University of Delhi) B-Tech 3rd Semester 1567 Data Communication and Computer Networks Question Paper

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Roll No.

S. No. of Question Paper : 1567

Unique Paper Code : 2341302

Name of the Paper : Data Communication and Computer Networks

Name of the Course : B.Tech. in Computer Science

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Semester : V

Duration : 3 Hours Maximum Marks : 75

(Write your Roll No. on the top immediately on receipt of this question paper.)

Attempt all the questions.

1. Write the layer in OSI Model that performs the following functions : 2
   1. Route determination

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   2. Flow control
   3. Mechanical and electrical interface
   4. Reliable process-to-process data transportation
   5. Reassembly of data packets
   6. Error correction and retransmission.

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2. Explain the following :
   1. Does the Nyquist theorem bit rate agree with the intuitive bit rate described in baseband transmission ? 3
   2. The signal-to-noise ratio is often given in decibels. Assume that SNR_dB = 36 and the channel bandwidth is 2 MHz. Calculate the theoretical channel. 3
   3. An analog signal carries 4 bits per signal element. If 1000 signal elements are sent per second, find the bit rate. 2
   4. Differentiate between binary PSK and Quadrature PSK.

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3. Briefly describe the following :
   1. Three phases required for the actual communication in a circuit-switched network. 3
   2. If there are no setup or teardown phases, how are the packets routed to their destinations in a datagram network ? 3
   3. Draw the pulse diagram for the bit stream 101110001011 for the following encoding technique : 6
      1. NRZ-L
      2. Manchester

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      3. Differential Manchester.
   4. How do multiple senders share the common transmission media in a network. List three techniques commonly used for this purpose. 4
   5. Explain bridge, router and gateway. 3
   6. Suppose a computer is moved from one building to another within a campus. Does the physical address need to change ? Does the IP address need to change ? Does it make a difference if the computer is a laptop ? Justify your answer. 3

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4. 1. Explain header field in IP protocol with diagram.
   2. An organization has been assigned the network address : 140.25.0.0 and it needs to create a set of subnets that support upto 25 hosts on each subnet. What is the subnet mask you would use to do this ? 3
   3. What is the maximum possible number of such subnets in the given network ? The use of special address must be avoided. 2

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5. What is the difference between a connection-oriented service and a connectionless service ? For each of the following tell whether it might be a connection oriented service, a connectionless service, both or neither : 2+3
   1. Connection establishment
   2. Data transmission
   3. Connection release.
6. 1. Write the port number of the following protocols : 2
      1. FTP

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      2. HTTP
      3. TELNET
      4. SMTP.
   2. What is DNS and how it resolves IP Address from URL ? 4

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7. Write short notes on any six of the following : 3x6=18
   1. ARQ
   2. Selective repeat ARQ
   3. TDM
   4. FSK

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   5. Hamming code
   6. CRC
   7. Packet switching
   8. Exponential back off algorithm
   9. Coaxial Cable Standards.

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