Sunday, 8 September 2013

Computer Network Objective Question


1-      A channel has a bit rate of 20 kbps and a propagation delay of 100 msec. For what sizes does stop and wait gives an efficiency of 50%.?
(a)   2500bits (b) 5000 bits (c) 1000 bits (d) 4000 bits
2-      A certain population of ALOHA users manages to generate 50 request/sec. If the time is slotted in units of 40 m.sec, then channel load would be
(a) 1.25            (b) 2                 (c) 1250                       (d) none of these
3-   An image is 1024*724 pixels with 3 bytes/ pixel. Assume the image is uncompressed.  How long will it take to transmit it over a 56 kbps modem channel?                                        (a)329.14 sec      (b)  325 sec             (c)  330 sec                  (d) 323.58 sec
4-      a group of 2n-1 routers are connected in a centralized binary tree with a router at each these node. Router I communicate with router J by sending a message to the root is the tree. The root the send the message pack down to J. drive an approximate expression for the mean number of hopes per message large n assuming that all router pairs are equally likely
(a)       2n-4   (b)   n-4/2   (c)    2-4/2       (d)    n-4
5-       Consider an error 364 kbps satellite channel used to send 512 bites data frames in one direction with very short ACK coming back the other ways what is the maximum through put for window size of one assume propagation time to be 270 msec.
(a)      3.99 kbps     (b)     8.5 kbps    (c)      6.78 kbps     (d)    data insufficient
6-      If a certain popular of ALOHA users manages to generates 100 request/sec. if the time is slotted in unit of 50 msec. then the chance of success on the first attempt would be
(a)      0.5  (b)      0.4   (c)     0.3       (d)    none of  these
7-      What is the probability of exactly 5 collision followed by a success when ALOHA users generate 50 requests/sec, if time is slotted in units of 40 msec.  ?
(a)     0.12      (b)     0.06521       (c)   0.3    (d) none of these
8-      A group of same station share a 56 kbps pure ALOHA channels. Each of these station output a 1000 bits frame on an average of one every 100 sec, even if the previous one not yet been sent, maximum number of station would be
(a)    1000     (b)     2000     (c)     2030         (d)    1030   
9-       Assume that 10000 reservation stations are competing for the use of a single slotted ALOHA channel. An average station makes 18 request/hours with a slot of 125 msec. calculate the channel load.
(a)    1/160      (b)    50        (c)      1/50       (c)   none of these
10-   CSMA/CD LAN of one Gbps is to be designed over 1 km cable without repeater. The minimum frame size that DLL should consider if cable support signal speed of 200000 km/sec, is
(a)     1000   (b)    5000    ( c)  100000 (d)    10000
11-    The length of a Base 5 cable is 2.5 km and the speed of propagation in the thick coaxial cable is 60% of the speed of light. the time required by a bit to travel from begging to the end of the network would be
(a)      55 msec.    (b)  12 msec.     (c)  data in sufficient     (d)   none of these
12-   100 km long cable runs at 1.536 mbps. The propagation speed in the cable is 2/3 speed of light. Number of bits fit in the cable would be
(a)    500    (b)  768    (c)  307    (d)   10000  
13-   You have an IP address of 156.233.42.56 with subnet mask of 7 bits. How many hosts and subnets are possible
(a)   126 hosts and 510 subnets
(b)    128 subnets and 512 host
(c)    510 host and 126 subnets
(d)   None of the above   
14-   You have a class C 192.168.10.0/28 network. How many usable subnets and hosts do you have?
(a)   16 subnets, 16 hosts
(b)    14 subnets, 14 hosts
(c)    20 subnets, 6 hosts
(d)   50 subnets, 2 hosts
15-   Which of following could be unicast?
(a)   10.3.1.27/30
(b)   255.255.255.255
(c)    172.16.128.255/18
(d)   192.168.10.48/29
16-   If the routing table has statics RIP and an IGRP route to the same network which route will be use to route packets by default?
(a)   Any route   (b)  RIP route   (c)  static route     (d)  IGRP route
17-   Which of the following as assertion is false about the internet protocol (IP)?
(a)   IT the possible for a computer to have multiple IP address
(b)   IP packets from the same source to same destination can take different routes in the network
(c)    IP ensures that a packet is forwarded if it is unable to reach its destination with in a given number of hops
(d)   The packet source can not set the route of an out going table in the routers on the way.
18-    Match the following-
       Group-I                                         Group II
(P)   SMTP                                      (1)   Application layer
(Q)  BGP                                         (2)   Transport layer
(R)   TCP                                          (3)   Data link layer
(S)   PPP                                           (4)   Network layer
                                                          (5)   Physical layer     
          (a) P-2,  Q-1,  R-3,  S-5  (b)  P-1, Q-4,  R-2,  S-3  (c)  P-1,  Q-2,  R-3,  S-4  (d) P-2, Q-4, R-1, S-3
19-  For stop and wait flow control, for n data packets are sent, the number of Acknowledgement needed is                              
(a)   n       (b)   2n     (c)   n-1    (d)    n+1

20-  Which of the following address does not belong to the same network (no sub netting)?
(1)    123.4.6.2     (II)     123.4.78.9     (III)   132.14.56.12    (iv)  123.4.0.0
(a)    Only (1)    (b)   only (1) and (II)    (c)  only (III)      (d)   only (1) , (II)  and  (IV)
21-   A network layer protocol defined by TCP/IP
(a)              TCP       (b)  UDP     (c)    IP     (d)  none of these
22- The file transfer protocol (FTP) requires a reliable transport service. Which protocol of the TCP/IP      suite does it use?
(a)    Transmission control protocol (TCP)
(b)   UDP
(c)    Telnet
(d)   All of the above
23- Transport layer is responsible for
(a)     Node to node delivery
(b)   End to end delivery
(c)    Station of station delivery
(d)   Host to host delivery
 24- Which of following statements are correct?
(a)     TCP is connection oriented and UDP is connectionless
(b)    UDP is connection oriented and TCP is connectionless
(c)    Both TCP and UDP is connection oriented
(d)    Both TCP and UDP is connectionless
25- ICMP stands for
(a)    Internet control message protocol
(b)   Internet connection message protocol
(c)    IP control message protocol
(d)   IP connection metro protocol
26-consider the IP address 128.252.144.84 what is the network ID and what is the node ID assume class full networking
(a)     0.0.0.0 and 128.252.144.84  (b)  128.0.0.0 and 252.144.84
(b)    128.252.0.0 and 144.84         (d)  128.252.144.0 and 144.84

27- Default subnet mask for class A, B and C are
(a)    0.255.255.255,  0.0.255.255,   255.255.0.0
(b)   255.0.0.0,  255.255.0.0,  255.255.255.0
(c)    255.255.255.0,  255.255.0.0,  255.0.0.0
(d)    0.0.0.0,  0.0.0.255,  0.0.255.255
28- You see the following subnet address. What is the subnet mask?
        128.255.4.0, 128.252.8.0, 128.252.12.0, 128.252.16.0
(a)   255.255.255.0   (b)   255.255.192.0   (c)   255.255.240.0    (d) 255.255.252.0
29- Bit stuffing is
(a)    Inserting a “o” in flag stream to avoid ambiguity
(b)   Inserting a “o” in user data stream to differentiate it with flag
(c)    Appending a nibble to the flag sequence
(d)   Appending a nibble to the user data stream
        30- Pick the correct statement about flooding
(a)    It is a type of isolated routing
(b)   It is a method in which every incoming packet is sent out on every out going line expect  the one by which it arrived
(c)    Selective flooding is a type in which the packet are sent to those lines that are going approximately in the right direction
(d)    All of the above  
         31- Which of the following network classes is reserved for multicast addressed only?
(a)    Class A (b)  class B  (c)  class C    (d)  class D
          32- The following are the steps towards encapsulation put them in order
1-      User input   2-  data    3-   frame     4- segment  5—data gram   6   bits
(a)     1-4-2-5-3-6  (b)  1-2-3-4-5-6   (c)  1-2-3-5-4-6   (d)  1-2-4-5-3-6
          33- Which of the following is not a function of the transport layer?
(a)    Provides  the ability to send unacknowledged packets
(b)   Can issue a “not ready”  indicator
(c)    Segment can be placed back into their correct sequence at the destination
(d)   Provides routing services
34- What is the broadcast address for the subnet that IP 255.255.255.248address                              
                          192.168.26.8, is a member of?
                     (a)  192.168.26.25  (b)   192.168.26.255  (c)  192.168.26.15   (d)  192.168.26.0
35- You have class B network with 12 bit subnet. How many subnet and hoe many hosts per                     
                   Subnets are available?
(a)    14,14  (b) 14,4094  (c)  4096,14  (d) 4094,14
36- Given the IP address 130.113.64.17/24 which statement is true?
(a)     130.113.64.0 is the network number
(b)    130.113.0.0 is the network number
(c)     130.0.0.0 is the network number
(d)    255.255.0.0 is the subnet mask
37- What is the primary purpose of FTP SERVER?
(a)    Simplify storage of file
(b)   Allow for backup storage of file
(c)    Report security violations of file
(d)   Facilitate transfer of file
38-   Your small company is growing and has decided to host a web page and dedicate a server
         For email. What protocol is used to support email traffic
(a)    ARP   (b)  DNS    (c)  SMT    (d)   FTP
39-   Which layer deals with?
                               Group- I                                                                                                Group- II
(i)                  File system transfer                                                                (A) Transport
(ii)                Virtual terminal emulation                                                   (B) Presentation
(iii)               Interposes communication                                                 (C) Session
(D) Application
40- Which answer best describe the function of ICMP?
(a)    ICMP is a distance vector routing protocol
(b)   ICMP provides control  and messaging capabilities   
(c)    ICMP provides host name to IP address resolution
(d)   ICMP determine the data link layer address from known IP address
41- In a board sense, a railway track is an example of
(a)    Simplex   (b) half duplex  (c) full duplex (d) all of the above
42- What are the benefits of LAN segmentation?
(i)                  A decrease in WAN costs
(ii)                An increase in collision domains
(iii)               Fewer network address
(iv)              An increase in bandwidth per user
(a)    Only  (i)   (b)  (ii) and (iv)   (c) only (iv)  (d)  all of the above
43- If you are using RSA algorithm for data security such that p=7 and q=11, then the legal value        
       Of encryption key would be
(a)    12         (b)  15              (c) 60           (d) 17
44- In RSA algorithm, if p= and q=11 then what could be the possible value of decryption key if       encryption key is 13?
(a)     13   (b)  37   (c)   60    (d)    17
45- For an RSA algo, if p= 5 and q=11 encryption key is 3, then encryption of “ a,b,c,d,e,f,g,h,I,j would give
(a)    1,2,3,4,5,6,7,8,9,10
(b)   4,5,6,7,9,10,11,12,13
(c)    1,8,27,9,15,10,14,10,17,13
(d)   1,8,27,9,15,51,13,17,14,10


         Answer
(1)   d  (2) b (3) a (4) a (5) c (6) d (7) b (8) d (9) a (10) d (11) d (12) b (13) c (14) b (15) c
 (16) c (17) d (18) b (19) a (20) c (21) c (22) a (23) b (24) a (25) a (26) c (27) b (28) d (29)b
(30) d (31) d (32) d (33) d (34) c (35) d (36) a (37) d (38) c (39) d (40) b (41) b (42) b (43) d
(44) b (45) d




        







  

                                                                                                    

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