Distributed Computing Quiz 1 BITS WILP - Mtec Software Systems - 2017

Distributed Computing Quiz 1

BITS WILP - Mtec Software Systems - 2017 

1. Consider the following statements:

(i) Middleware provides interoperability among distributed objects.

(ii) Middleware is independent of hardware platforms.

(iii) Middleware is dependent on operating systems.

Which of the following is true?

Select one:
a. (i) only
b. (iii) only
c. (i), (ii) and (iii)
d. (i) and (ii)

Ans: (i) and (ii)

2. The master variable used in the Spezialetti–Kearns algorithm denotes the

Select one:
a. identifier of the process that initiated the algorithm
b. identifier of the process that has received a marker
c. identifier of a process that has already recorded its snapshot
d. identifier of the process that has received a marker along each of its incoming channels

Ans: identifier of the process that initiated the algorithm

3. The number of stages in a 64-input and 64-output Omega network is

Select one:
4
8
6
16

Ans: 6

4. Which of the following statement is false in context of Lai-Yang algorithm?

Select one:
every process is initially white
a message sent by a white process is colored white
a message sent by a red process is colored red
a process turns red when it receives a marker

Ans: a process turns red when it receives a marker


5. A cut is inconsistent if

Select one:
more than one message cross the cut from the FUTURE to the PAST
any message crosses the cut from the PAST to the FUTURE
at least one message crosses the cut from the FUTURE to the PAST
no message crosses the cut

Ans: at least one message crosses the cut from the FUTURE to the PAST

6. eyjdenotes


Select one:
the set of events that have occurred at process pj
the yth event that has occurred at process pj
the yth internal event that has occurred at process pj
the event at process pj whose time duration is y units

Ans: the yth event that has occurred at process pj

7. For two events a and b having vector timestamps vx and vy respectively, if a causally affects b, then

Select one:
vx = vy
vx > vy
vx || vy
vx < vy

Ans: vx < vy

8. Global state of a distributed system is

Select one:
a collection of the local states of the channels only
a collection of the local states of the processes and the channels
a collection of the local states of the processes only
a collection of the local states of a set of empty channels

Ans: a collection of the local states of the processes and the channels

9. Which of the following properties is not satisfied by scalar clocks?

Select one:
strong consistency
total ordering
consistency
event counting

Ans: strong consistency

10. How many processing modes are defined in Flynn's taxonomy?

Select one:
5
6
3
4

Ans: 4

11. Which of the following is true?

Select one:
send(mij) ∉∉ LSi ⇒ mij ∉∉ SCij ⊕⊕ rec(mij)  ∉∉ LSj

 send(mij) ∉∉ LSi ⇒ mij ∉∉ SCij

 send(mij) ∉∉ LSi ⇒ mij ∉∉ SCij ∧ rec(mij)  ∉∉ LSj


send(mij) ∉∉ LSi ⇒ mij ∉∉ SCij ∨∨ rec(mij)  ∉∉ LSj


Ans: send(mij) ∉∉ LSi ⇒ mij ∉∉ SCij ∧ rec(mij)  ∉∉ LSj

12. Which of the following is true of the UMA model?

Select one:
software is very loosely coupled
interconnection network to access memory may be a multistage switch
processors are of different types
each processor runs a different operating system

Ans: interconnection network to access memory may be a multistage switch

13. A system supporting causal ordering model satisfies

Select one:
for messages mij and mkj , if send(mij) → rec(mkj), then rec(mij) → send(mkj)
for messages mij and mik , if send(mij) → send(mik), then rec(mij) → rec(mik)
for messages mij and mkj , if send(mij) → send(mkj), then rec(mij) || rec(mkj)
for messages mij and mkj , if send(mij) → send(mkj), then rec(mij) → rec(mkj)

Ans: for messages mij and mkj , if send(mij) → send(mkj), then rec(mij) → rec(mkj)

14. The number of processor and memory units in a 5-dimensional hypercube is

Select one:
16
32
25
64

Ans: 32

15. A global state is strongly consistent iff the global state

Select one:
is consistent and transitless
follows the FIFO model
is transitless
follows the causal ordering model

Ans: is consistent and transitless

16. Concurrency of a distributed program is defined as

Select one:
the ratio of the number of local operations to twice the total number of operations
the ratio of the total number of operations to twice the number of local operations
the ratio of the number of local operations to the total number of operations
the ratio of the total number of operations to the number of local operations

Ans: the ratio of the number of local operations to the total number of operations

17. The system of vector clocks is strongly consistent if


Select one:
the dimension of vector clocks is one less than the total number of processes in the distributed computation
the dimension of vector clocks is at least equal to the total number of processes in the distributed computation
the dimension of vector clocks is half of the total number of processes in the distributed computation
the dimension of vector clocks is one third of the total number of processes in the distributed computation

Ans: the dimension of vector clocks is at least equal to the total number of processes in the distributed computation

18. The termination criterion for the Chandy-Lamport global snapshot recording algorithm is that
Select one:
each process has received a marker on all of its incoming channels
each process has sent a marker to every other process
each process has received a marker from each of the other processes
each process has sent a marker on all of its outgoing channels

Ans: each process has received a marker on all of its incoming channels

19. Which of the following is false for a distributed system?

Select one:
has no shared memory
communicate using message passing
individual computers may be connected via LAN or WAN
has a common clock

Ans: has a common clock

20. CORBA stands for

Select one:
Cyclic Obfuscated Request Broker Architecture
Creative Object Request Broker Architecture
Common Object Request Broker Architecture
Coordinated Online Request Broker Architecture

Ans: Common Object Request Broker Architecture

21. For Butterfly and Omega networks, paths from different inputs to any one output constitute a

Select one:
loop
forest
spanning tree
cycle

Ans: spanning tree

22. ei →→ ej  denotes that


Select one:
ei only directly causally affects ej
ei and ej are concurrent
ej directly or transitively causally affects ei
ei directly or transitively causally affects ej

Ans: ei directly or transitively causally affects ej

23. For an n-input and n-output Omega network, output i of a stage is connected to input j of next stage if j = 2i + 1 - n for

Select one:
n/2 < i < n - 1
n/2 < i < n
n/2 <= i <= n - 1
n/2 <= i <= n

Ans: n/2 <= i <= n - 1

24. The number of switches in a single stage of an n-input and n-output Butterfly network is

Select one:
n
n/4
2n
n/2

Ans: n/2

25. A system of logical clocks is strongly consistent if the following condition is satisfied

Select one:
for 2 events ei and ej, ei →→  ej ⇔⇔ C(ei) >= C(ej)

 for 2 events ei and ej, ei →→  ej ⇔⇔ C(ei) = C(ej)

 for 2 events ei and ej, ei ||  ej ⇔⇔ C(ei) < C(ej)

 for 2 events ei and ej, ei →→  ej ⇔⇔ C(ei) < C(ej)

 Ans: for 2 events ei and ej, ei →→  ej ⇔⇔ C(ei) < C(ej)