UGC NET JULY 2018 (Computer Science And Applications Paper-II) (Question 46-50)

UGC NET JULY 2018 (Computer Science And Applications Paper-II) (Question 46-50)

Q 46. Which of the following statements are true ?

(a) Three broad categories of Networks are

     (i) Circuit Switched Networks

    (ii) Packet Switched Networks

    (iii) Message Switched Networks

(b) Circuit Switched Network resources need not be reserved during the set up phase.

(c) In packet switching there is no resource allocation for packets.

Code :

1. (a) and (b) only
2. (b) and (c) only
3. (a) and (c) only
4. (a), (b) and (c)

Answer: 3). (a) and (c) only

Q 47. In Challenge-Response authentication the claimant ________.

1. Proves that she knows the secret without revealing it
2. Proves that she doesn’t know the secret
3. Reveals the secret
4. Gives a challenge

Answer: 1). Proves that she knows the secret without revealing it

Reason: Challenge-Response authentication is a computer security protocol in which one party ask a question and another party must provide a valid answer. I.e. she knows the secret without revealing it or will provide the secret when it is asked.

Q 48. Decrypt the message “WTAAD” using the Caesar Cipher with key=15.

1. LIPPS
2. HELLO
3. OLLEH
4. DAATW

Answer: 2). HELLO
Reason: In Ceaser cipher algorithm encryption and decryption takes place. During encryption right shift takes place depending upon the key and in decryption left shift takes place depending on key. In the given question key value is 15 and decryption is asked:
Given message is WTAAD
Left shift 15 on W is H
Left shift 15 on T is E
Left shift 15 on A is L
Left shift 15 on A is L
Left shift 15 on D is O
The decrypted message will HELLO.

Q 49. To guarantee correction of upto t errors, the minimum Hamming distance dmin in a block code must be ________.

1. t+1
2. t−2
3. 2t−1
4. 2t+1

Answer: 4). 2t+1

Q 50. Encrypt the Message “HELLO MY DEARZ” using Transposition Cipher with

1. HLLEO YM AEDRZ
2. EHOLL ZYM RAED
3. ELHL MDOY AZER
4. ELHL DOMY ZAER

Answer: 3). ELHL MDOY AZER 
Reason:
In question encryption of given message using Transposition Cipher with 

Given message is “HELLO MY DEARZ” Now arrange them in group of 4
I.e. HELL OMYD EARZ
i.e. replace the following...

• second character in above format to the first place
• fourth character to the second place
• first character to the third place
• third character to the fourth place.

Encrypted message will be ELHL MDOY AZER.

Read More

UGC NET JULY 2018 (Computer Science And Applications Paper-II) (Question 41-45)

UGC NET JULY 2018 (Computer Science And Applications Paper-II) (Question 41-45)

Q 41. A slotted ALOHA network transmits 200-bit frames using a shared channel with a 200 Kbps bandwidth. Find the throughput of the system, if the system (all stations put together) produces 250 frames per second :

1. 49
2. 368
3. 149
4. 151

Answer: 1). 49


Solution : Here G is 1/4, Therefore S = G x e^-G = 0.195 (19.5), 
this means 250 x 0.195 = 49. Only 49 frames out of 250 will probably survive.

Q 42. The period of a signal is 100 ms. Its frequency is _________.

1. 100³ Hertz
2. 10⁻² KHz
3. 10⁻³ KHz
4. 10⁵ Hertz

Answer: 2). 10⁻² KHz
Solution: Explanation: We know that:
frequency(f) = 1 / Time period(T)
Given time period(T) = 100 ms
f = 1 / 100ms
f = 1000 / 100000 ms
We know that 1000 ms = 1 sec and we can write 1000 as 1 k, i.e. f = 1k / 100s
f = 10^-2 kHz (1 / s = Hz) So, option (B) is correct.

Q 43. The dotted-decimal notation of the following IPV4 address in binary notation is _________.

10000001 00001011 00001011 11101111

1. 111.56.45.239
2. 129.11.10.238
3. 129.11.11.239
4. 111.56.11.239

Answer: 3). 129.11.11.239

Explanation:  IPV4 address = 10000001 00001011 00001011 11101111
10000001 = 129,       00001011 = 11,     00001011 = 11,     11101111 = 239

IPV4 address 10000001 00001011 00001011 11101111 is equivalent to 129.11.11.239
So, option (C) is correct.

Q 44. Which of the following statements are true ?

(a) Advanced Mobile Phone System (AMPS) is a second generation cellular phone system.

(b) IS – 95 is a second generation cellular phone system based on CDMA and DSSS.

(c) The Third generation cellular phone system will provide universal personnel communication.

Code :

1. (a) and (b) only
2. (b) and (c) only
3. (a), (b) and (c)
4. (a) and (c) only

Answer: 2). (b) and (c) only
Reason:

• Advanced Mobile Phone System (AMPS) is a First generation cellular phone system.False
• IS – 95 is a second generation cellular phone system based on CDMA and DSSS.True 
• The Third generation cellular phone system will provide universal personnel communication.True

SO, option (B) is correct.

45. Match the following symmetric block ciphers with corresponding block and key sizes :

Answer: 2). (ii)     (iv)       (i)      (iii)

Reason:

Data Encryption Standard(DES) block cipher uses block size 64 and key size 64

International Data Encryption Algorithm (IDEA) uses block size 64 and key size 12.

BLOW FISH is the relacement for DES or IDEA, it uses block size 64 and key size ranges between 32 and 448

Advanced Encryption Standard (AES) uses block size 128 and key sizes 128, 192, 256

Read More

UGC NET JULY 2018 (Computer Science And Applications Paper-II) (Question 37-40)

UGC NET JULY 2018 (Computer Science And Applications Paper-II) (Question 37-40)

Q 37. Context sensitive language can be recognized by a :

(1) Finite state machine

(2) Deterministic finite automata

(3) Non-deterministic finite automata

(4) Linear bounded automata

Answer:  (4) Linear bounded automata

Q 38. The set A={ 0ⁿ 1ⁿ 2ⁿ | n=1, 2, 3, ……… } is an example of a grammar that is :

(1) Context sensitive

(2) Context free

(3) Regular

(4) None of the above

 

Answer:  (1) Context sensitive

Q 39. A bottom-up parser generates :

(1) Left-most derivation in reverse

(2) Right-most derivation in reverse

(3) Left-most derivation

(4) Right-most derivation

 

Answer:  (2) Right-most derivation in reverse

Q 40. Consider the following statements( ) :

S1 : There exists no algorithm for deciding if any two Turing machines M1 and M2 accept the same language.

S2 : The problem of determining whether a Turing machine halts on any input is undecidable.

Which of the following options is correct ?

(1) Both S1 and S2 are correct

(2) Both S1 and S2 are not correct

(3) Only S1 is correct

(4) Only S2 is correct

 

Answer:  (1) Both S1 and S2 are correct

Read More

UGC NET JULY 2018 (Computer Science And Applications Paper-II) (Question 35-36)

UGC NET JULY 2018 (Computer Science And Applications Paper-II) (Question 35-36)

Q 35. To obtain a string of n Terminals from a given Chomsky normal form grammar, the number of productions to be used is :

(1) 2n−1

(2) 2n

(3) n+1 

(4) n²

 

Answer:   (1) 2n−1 

Q 36. Consider the following two Grammars :

Which of the following option is correct ?

(1) Only G₁ is ambiguous

(2) Only G₂ is ambiguous

(3) Both G₁ and G₂ are ambiguous

(4) Both G₁ and G₂ are not ambiguous

Answer:  (3) Both G₁ and G₂ are ambiguous

Read More

UGC NET JULY 2018 (Computer Science And Applications Paper-II) (Question 33-34)

UGC NET JULY 2018 (Computer Science And Applications Paper-II) (Question 33-34)

Q 33. A pushdown automata behaves like a Turing machine when the number of auxiliary memory is :

(1) 0

(2) 1

(3) 1 or more

(4) 2 or more

Answer: (4) 2 or more 

Reason : A pushdown automata behaves like a Turing machine when the number of auxiliary memory is 2 or more. PDA with 2 or more auxiliary memory have same expressive power. Generally PDA has one auxiliary memory.

Q 34. Pushdown automata can recognize language generated by_________.

(1) Only context free grammar

(2) Only regular grammar

(3) Context free grammar or regular grammar

(4) Only context sensitive grammar

Answer: (3) Context free grammar or regular grammar

Reason : Pushdown automata can recognize language generated by Context free grammar or regular grammar. 

Read More

UGC NET JULY 2018 (Computer Science And Applications Paper-II) (Question 32)

UGC NET JULY 2018 (Computer Science And Applications Paper-II) (Question 32)

Q 32. The finite state machine given in figure below recognize: 

1. any string of odd number of a’s
2. any string of odd number of b’s
3. any string of even number of a’s and odd number of b’s
4. any string of odd number of a’s and odd number of b’s

Answer :  4. any string of odd number of a’s and odd number of b’s

Read More

UGC NET JULY 2018 (Computer Science And Applications Paper-II) (Question 31)

UGC NET JULY 2018 (Computer Science And Applications Paper-II) (Question 31)

Q 31. Two finite state machines are said to be equivalent if they :
 

1. Have the same number of edges
2. Have the same number of states
3. Recognize the same set of tokens
4. Have the same number of states and edges

 Answer : 3. Recognize the same set of tokens

Two finite state machine are said to be equivalent if, starting from their respective initial states, they will produce the same output sequence when they are given the same input sequence. That implies they must recognize the same set of tokens.

Definition 1 (equivalence of finite state machines): Two finite state machines M1 and M2 are
equivalent (M 1 E M2) if they have the same input and output alphabets and if, starting from
their respective initial states, they produce the same output for any input string.

Definition 2 (equivalence of states): Two states p (of finite state machine M1) and q (of
machine M2, which may or may not be the same as M1) are equivalent (p 5 q) if the machines
they belong to have the same input and output alphabets and if, for any input string, machine M1
started from state p produces the same output as machine M2 started from state q.

Definition 3 (strongly connected machines): A finite state machine M is strongly connected if,
for any states 3 and r in the state space of M, there exists a finite sequence of transitions that
takes M from state 3 to state r.

Read More

UGC NET JULY 2018 (Computer Science And Applications Paper-II) (Question 30)

UGC NET JULY 2018 (Computer Science And Applications Paper-II) (Question 30)

Q 30. Consider a Boolean function of ‘n’ variables. The order of an algorithm that determines whether the Boolean function produces a output 1 is :
 

1. Logarithmic
2. Linear
3. Quadratic
4. Exponential 

 Answer : 4. Exponential 

 

Read More