DMRC (Delhi Metro) Exam Papers - Computer Science
DMRC (Delhi Metro) Exam Papers - Computer Science
1. When two numbers are added in excess-3 code and the sum is less than 9, then in order to get the correct answer it is necessary to
(a) subtract 0011 from the sum
(b)add 0011 to the sum
(C) subtract 0110 from the sum
(d)add OllOto the sum
2. A graph with ‘en” vertices and n-I edges that Is not a tree, is
(a) Connected
(b) Disconnected
(C) Euler
(d) A circuit
3. If a graph requires k different colours for its proper colouring, then the chromatic number of the graph is
(a)1
(b)k
(c) k-I
(d) k12
4. Are adblt can be read
(a) and written by CPU
(b) and written by peripheral
(c) by pheripheral and written by CPU
(d) by CPU and written by the peripheral
5. The term “aging” refers to
(a ) booting up the priority of a process in multi-level of
queue without feedback.
(b) gradually increasing the priority of jobs that wait in the system for a long
time to remedy infinite blocking.
(C) keeping track of the following a page has been in memory for the purpose of
LRU replacement
(d) letting job reside in memory for a certain amount of time so that the number
of pages required can be estimated accurately
6. Consider a set of n tasks with known runtirnes r1, r2 ……. r to be run on a unlprocessor machine. Which of the following processor scheduling algorithms will result in the maximum throughput?
a) Round Robin
b) Shortest job first
c) Highest response ratio next
d) first cum first served
7. The principal of locality of reference justifies the use of
(a) virtual memory
(b) interrupts
(c) main memory
(d) cache memory
8. The five Items: A, B, C, D, and E are pushed in a stack, one after the other starting from A. The stack is popped four times and each element is Inserted in a queue. Then two elements are deleted from the queue and pushed back on the stack. Now one item is popped from the stack. The popped item is
(a)A
(b)B
(c)C
(d)D
9. Round Robin scheduling is essentially the pre-emptive version of
a) FIFO
b) Shortest Job First
c) Shortest remaining time
d) Longest remaining time
10. Assume that each character code consists of 8 bits. The number of characters that can be transmitted per second through an synchronous serial line at 2400 baud rate, and with two stop bits is
(a)109
(b) 216
(c)218
(d)219
11. If the bandwidth of a signal is 5 kHz and the lowest frequency is 52 kHz, what is the highest frequency
(a) 5 kHz
(b) 10kHz
(C) 47 kHz
(d) 57 kHz
12. An Ethernet hub
(a) functions as a repeater
(b) connects to a digital PBX
(C) connects to a token-ring network
(d) functions as a gateway
13. Phase transition for each bit are used in
(a) Amplitude modulation
(b) Carrier modulation
(c) Manchester encoding
(d) NRZ encoding
14. Which of the foIlowng is printed as a result of the call demo (1234)?
a) 1441
b) 3443
C) 12344321
d) 43211234
15. Bit stuffing refers to
(a) inserting a ‘O’in user stream to differentiate it with a
flag
(b) inserting a ‘0’ in flag stream tc avoid ambiguity
(C) appending a nibble to the flag sequence
(d ) appending a nibble to the use data stream
16. What is the name of the technique in which the operating system of a computer executes several programs concurrently by switching back and forth between them?
(a) Partitioning
(b) Multi tasking
(C) Windowing
(d) Paging
17. If there are five routers and six networks in an ntranet using link state routing, how many routing tables are there?
(a)1
(b)5
(c)6
(d)11
18. Virtual memory is
a) Part of Main Memory only used for swapping
b) A technique to allow a program, of size more than the size of the main
memory, town
C) Part of secondary storage used in program execution
d) None of these
19. The level of aggregation of information required for operational control is
(a) Detailed
(b) Aggregate
(C) Qualitative
(d) None of the above
20. in decimal system is equivalent to in octal system
a) 0.60
b) 0.52
c)0.54
d) 0.50
21. In an SR latch made by cross coupling two NAND gates, if both S and R inputs are set to 0, then it will result in
a) Q=O, QO= I
b) Q=1,Q0=00=1, QO = 1
Indeterminate states
In comparison with static RAM memory, the dynamic RAM memory has
a) lower bit density and higher power consumption
b) higher bit density and higher power consumption
c) lower bit density and lower power consumption
d) higher bit density and lower power consumption.
22. Disk requests are received by a disk drive for cylinder 5, 25, 18, 3, 39, 8 and 35 in that order A seek takes 5 msec per cylinder moved. How much seek time is needed to serve these requests for a Shortest Seek First (SSF) algorithm? Assume that the arm is at cylinder ?,O when the last of these requests is made with none of the requests yet served
a) 125 msec
b) 295 msec
c) 575 msec
d) 750 msec
23. Consider a system having ‘m’ resource.s of the same type. The resources are shared by 3 processes A,B,C, which have peak time demands of 3,4,6 respectively. The minimum value of ‘m’ that ensures that deadlock will never occur is
(a)11
(b) 12
(c) 13
(d)14
24. A task in a blocked state
a) is executable
b) is running
C) must still be placed in the run queues
d) Is waiting for some temporarily unavailable resources.
25. Semaphores
a) synchronize critical resources to prevent deadlock
b) synchronize critical resources to prevent contention
c) are used to do I/O
d) are used for memory management.
26. Which commands are used to control access over objects in relational database?
a) CASCADE & MVD
b) GRANT & REVOKE
c) QUE & QUIST
d) None of these
27. Which of the following is aggregate function in SQL?
a) Avg
b) Select
c) Ordered by
d) distinct
28. A view of a database that appears to an application program Is known as
a) Schema
b) Subschema
C) Virtual table
d) None of these
29. Armstrong’s inference rule doesn’t determine
a) Reflexivity
b) Augmentation
c) Transitivity
d) Mutual dependency
30. Which operation is used to extract specified columns from a table
a) Project
b) Join
C) Extract
d) Substitute
31. In the Big-Endian system, the computer stores
a) MSB of data in the lowest memory address of data unit
b) LSB of data in the lowest memory address of data unit
c) MSB of data in the highest memory address of data unit
d) LSB of data in the highest memory address of data unit
32. BCNF is not used for cases where a relation has
a) Two (or more) candidate keys
b) Two candidate keys and composite
c) The candidate key overlap
d) Two mutually exclusive foreign keys
33. Selection sort a’gorithm design technique is an example of
a) Greedy method
b) Divide-and-conquer
c) Dynamic Programming
d) Backtracking
34. Which of the following RAID level provides the highest Data Transfer Rate (Read IWrite)
a) RAID I
b) RAID 3
C) RAID 4
d) RAID 5
35. Which of the following programming language(s) provides garbage collection automatically
a) Lisp
b) C++
c) Fortran
d)C
36. Which of the following is correct with respect to Two phase commit protocol?
(a) Ensures serializability
(b) Prevents Deadlock
(C) Detects Deadlock
(d) Recover from Deadlock
37. Let X be the adjacency matrix of a graph G with no self loops. The entries along the principal diagonal of X are
(a) all zeros
(b) all ones
(C) both zeros and ones
(d) different
38. I Which of these is not a feature of WAP 2.0
(a) Push & Pull Model
(b) Interface to a storage device
(C) Multimedia messaging
(d) Hashing
39. I Feedback queues
(a) are very simple to implement
(b) dispatch tasks according to execution characteristics
(c) are used to favour real time tasks
(d) require manual intervention to implement properly
40. Which of the following Is not a UML DIAGRAM?
(a) Use Case
(b) Class Diagram
(c) Analysis Diagram
(d) Swimlane Diagram
41. Silly Window Syndrome is related to
(a) Error during transmission
(b) File transfer protocol
(C) Degrade in TCP performance
(d) Interface problem
41. To execute al! loops at their boundaries and within their operational bounds is an example of
(a) Black Box Testing
(b) Alpha Testing
(C) Recovery Testing
(d) White Box Testing
42. SSL is not responsible for
(a) Mutual authentication of client & server
(b) Secret communication
(C) Data Integrity protection
(d) Error detection & correction
43. A rule in a limited entry decision table is a
(a) row of the table consisting of condition entries
(b) row of the table consisting of action entries
(C) column of the table consisting of condition entries and the corresponding
action entries
(d) columns of the table consisting of conditions of the stub
44. The standard for certificates used on Internet is a)X.25
b) X.301
c) X.409
d) X.509
45. Hashed message is signed by a sender using
a) his public key
b) his private key
C) receivers public key
d) receivers pnvate key
46. A physical DFD specifies
a) what processes will be used
b) who generates data and who processes it
C) what each person in an organization does
d) which data will be generated
47. In UML diagram of a class
a) state of object cannot be represented
b) state is irrelevant
C) state is represented as an attribute
d) state is represented as a result of an operation
48. Which of the following models is used for software reliability?
a) Waterfall
b) Musa
C) COCOMO
d) Rayleigh
49. Djikstra’s algorithm is used to
a) Create LSAs
b) Flood an internet with information
C) Calculate the routing tables
d) Create a link state database