ISRO CS 2009

Refer: GATE-CS-2003 | Question 90

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.

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.

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.

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.

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.

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.

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.

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.