ISRO CS 2009

Question 1
The subnet mask for a particular network is 255.255.31.0. Which of the following pairs of IP addresses could belong to this network?
A
172.57.88.62 and 172.56.87.23
B
10.35.28.2 and 10.35.29.4
C
191.203.31.87 and 191.234.31.88
D
128.8.129.43 and 128.8.161.55
IP Addressing    ISRO CS 2009    
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Question 1 Explanation: 
Question 2
In networking, UTP stands for
A
Unshielded T-connector port
B
Unshielded twisted pair
C
Unshielded terminating pair
D
Unshielded transmission process
Misc Topics in Computer Networks    ISRO CS 2009    
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Question 2 Explanation: 
UTP stands for unshielded twisted pair. It consists of two insulated copper wires which have been twisted around one another which helps to control signal degradation due to interference. So, option (C) is correct.
Question 3
The address resolution protocol (ARP) is used for
A
Finding the IP address from the DNS
B
Finding the IP address of the default gateway
C
Finding the IP address that corresponds to a MAC address
D
Finding the MAC address that corresponds to an IP address
CN Data Link Layer    ISRO CS 2009    
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Question 3 Explanation: 
Address Resolution Protocol (ARP) is a protocol for mapping an Internet Protocol address (IP address) to a physical machine address that is recognized in the local network. It is a low-level network protocol for translating network layer addresses into link layer addresses. So, option (D) is correct.
Question 4
Which of the following is a MAC address?
A
192.166.200.50
B
00056A:01A01A5CCA7FF60
C
568, Airport Road
D
01:A5:BB:A7:FF:60
CN Data Link Layer    ISRO CS 2009    
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Question 4 Explanation: 
The size of MAC address is 48 bits. It contains 12 hexadecimal numbers inside six groups, with each group containing two hexadecimal number each. So,01:A5:BB:A7:FF:60 is the valid MAC address.
Question 5
What is the primary purpose of a VLAN?
A
Demonstrating the proper layout for a network
B
Simulating a network
C
To create a virtual private network
D
Segmenting a network inside a switch or device
CN Data Link Layer    ISRO CS 2009    
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Question 6
SHA-1 is a
A
encryption algorithm
B
decryption algorithm
C
key exchange algorithm
D
message digest function
Network Security    ISRO CS 2009    
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Question 6 Explanation: 
SHA-1 (Secure Hash Algorithm 1) is a cryptographic hash function which takes an input and produces a 160-bit (20-byte) hash value known as a message digest which is 40 digits long. So, it is a message digest function. Option (D) is correct.
Question 7
Advanced Encryption Standard (AES) is based on
A
Asymmetric key algorithm
B
Symmetric key algorithm
C
Public key algorithm
D
Key exchange
Network Security    ISRO CS 2009    
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Question 7 Explanation: 
AES is a symmetric key algorithm i.e. same key is used for encryption and decryption process. The AES replaced the DES with new and updated features- Block encryption implementation. 128-bit group encryption with 128, 192 and 256-bit key lengths. Symmetric algorithm requiring only one encryption and decryption key. AES design is based on a substitution-permutation network (SPN). Data security for 20-30 years. Easy overall implementation. So, option (B) is correct.
Question 8
The primary purpose of an operating system is
A
To make most efficient use of the computer hardware
B
To allow people to use the computer
C
To keep systems programmers employed
D
To make computers easier to use
OS Input Output Systems    ISRO CS 2009    
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Question 8 Explanation: 
An operating system has three main functions: (1) manage the computer's resources, such as the central processing unit, memory, and other input - output sources (2) establish a user interface, and (3) execute and provide services for applications software. OS provides an interface between the user and the hardware and thus making the computer easy to use for the user but the primary function of OS is to manage the hardware in the most efficient way. So, option (A) is correct.
Question 9
Which is the correct definition of a valid process transition in an operating system?
A
Wake up: ready → running
B
Dispatch: ready → running
C
Block: ready → running
D
Timer runout: ready → running
OS Process Management    ISRO CS 2009    
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Question 9 Explanation: 
The state transition diagram of a process(preemptive scheduling): Option 1: Wake up: ready → running It is incorrect as when a process wakes up it is shifted from blocked state to ready state and not from ready to running. Option 2: Dispatch: ready → running It is correct as the dispatcher selectively assigns the CPU to one of the process in the ready queue based on a well defined algorithm. Option 3: Block: ready → running It is incorrect as a process is blocked when it is either pre-empted by some other process or due to some i/o operation. So when a process gets blocked it shifts from running state to blocked state. Option 4: Timer runout: ready → running When the time duration of execution of a process expires, the timer interrupts and the process shifts from the running state to ready queue. So, option (B) is correct.
Question 10
The correct matching of the following pairs is
(A) Disk check              (1) Roundrobin
(B) Batch processing        (2) Scan
(C) Time sharing            (3) LIFO
(D) Stack operation         (4) FIFO
A
A B C D
 3 4 2 1
B
A B C D
4 3 2 1
C
A B C D
3 4 1 2
D
A B C D
2 4 1 3
OS Process Management    ISRO CS 2009    
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Question 10 Explanation: 
Option (D) is correct: A: Disk check- (2) Various scan algorithms are used for disc checking like FCFS, SSTF, SCAN, C-SCAN, LOOK, C-LOOK etc. B: Batch Processing- In batch processing processes are strictly executed in FIFO order. C: Time sharing- In Round Robin scheduling algorithm, the processes perform CPU execution in time sharing manner as there is a fixed time quanta associated with each process for execution. D: Stack operation- stack operates in last in first out manner.
There are 80 questions to complete.


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