UPSC CISF-AC-EXE Archives

1. Which one of the following protocols is used for secure communication

Which one of the following protocols is used for secure communication over computer network ?

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HTTP

DHCP

SMTP

HTTPS

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HTTPS (Hypertext Transfer Protocol Secure) is the protocol used for secure communication over computer networks, particularly for accessing websites. It combines the standard HTTP protocol with an encryption layer, typically Transport Layer Security (TLS) or its predecessor Secure Sockets Layer (SSL). This encryption ensures that data transmitted between the user’s browser and the server is protected from eavesdropping and tampering.
– HTTP is the standard, non-secure web protocol.
– DHCP is used for assigning IP addresses.
– SMTP is used for sending email.

– HTTPS adds a security layer (TLS/SSL) to HTTP.
– It encrypts data exchanged between client and server, ensuring confidentiality and integrity.

While SMTP can be secured using extensions like STARTTLS or SMTPS, the base SMTP protocol itself is not secure. Similarly, other protocols have secure variants (e.g., SFTP for FTP, SSH for Telnet). HTTPS is the standard secure version for web communication.

2. Which one of the following is an Information Security Management Stand

Which one of the following is an Information Security Management Standard ?

ISO 9001

ISO 14001

ISO 27001

ISO 17025

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ISO 27001 is an international standard for information security management systems (ISMS). It provides a framework for organizations to establish, implement, operate, monitor, review, maintain, and improve their information security. The other standards listed pertain to different management areas: ISO 9001 is for quality management, ISO 14001 is for environmental management, and ISO 17025 is for testing and calibration laboratories.

– ISO 27001 specifically addresses Information Security Management Systems (ISMS).
– Other ISO standards cover different management disciplines.

ISO 27001 is part of the ISO/IEC 27000 family of standards, which focuses on information security. Compliance with ISO 27001 demonstrates an organization’s commitment to managing information security risks effectively.

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3. Which one of the following digital circuits is used as the basic compo

Which one of the following digital circuits is used as the basic component for storing data ?

Counter

Flip-flop

Derived logic gates

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The basic component used for storing a single bit of data (a 0 or a 1) in sequential digital circuits is the flip-flop. A flip-flop is a bistable multivibrator, meaning it can exist in one of two stable states, which represent the two binary values. Registers and counters are built using multiple flip-flops connected in specific configurations to store multiple bits or count events, respectively. Derived logic gates (like NAND, NOR) are fundamental building blocks for constructing sequential circuits, including flip-flops, but they themselves do not inherently store data in a stable state over time without feedback loops forming a flip-flop.

– A flip-flop is a sequential circuit that can store one bit of data.
– Registers and counters are higher-level components built from flip-flops.
– Logic gates are combinatorial and do not store data unless configured in a sequential manner (e.g., within a flip-flop).

Common types of flip-flops include SR (Set-Reset), D (Data), JK, and T (Toggle) flip-flops. They are the fundamental memory elements in synchronous and asynchronous sequential circuits.

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4. Which one of the following bits is reserved for the sign bit in signed

Which one of the following bits is reserved for the sign bit in signed-magnitude representation ?

LSB

MSB

Exactly the middle of the bits

Second bit from left side

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In signed-magnitude representation, the most significant bit (MSB), which is the leftmost bit, is reserved to indicate the sign of the number. By convention, a 0 in the MSB indicates a positive number, and a 1 in the MSB indicates a negative number. The remaining bits represent the absolute magnitude of the number.

– Signed-magnitude representation uses one bit for the sign and the rest for magnitude.
– The MSB is the standard bit used for the sign.
– MSB = 0 for positive, MSB = 1 for negative.

Other signed number representations include one’s complement and two’s complement. While they also use the MSB as the sign bit, the way the magnitude of negative numbers is represented differs from signed-magnitude. Two’s complement is the most common method used in computers today because it simplifies arithmetic operations.

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5. Which one of the following is the equivalent decimal value of Hexadeci

Which one of the following is the equivalent decimal value of Hexadecimal number 4A9.2 ?

1192.125

1193.125

1192.0125

1193.0125

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To convert a hexadecimal number to a decimal number, we multiply each digit by the corresponding power of the base (16) and sum the results. The weights for positions to the left of the decimal point are increasing positive powers of 16 (16^0, 16^1, 16^2, etc., from right to left). The weights for positions to the right of the decimal point are increasing negative powers of 16 (16^-1, 16^-2, etc., from left to right).
The hexadecimal number is 4A9.2. The digits are 4, A, 9, and 2. The hexadecimal digit ‘A’ corresponds to decimal 10.
Conversion:
4 * 16^2 + A * 16^1 + 9 * 16^0 + 2 * 16^-1
= 4 * 256 + 10 * 16 + 9 * 1 + 2 * (1/16)
= 1024 + 160 + 9 + 0.125
= 1193 + 0.125
= 1193.125

– Hexadecimal numbers are converted to decimal by summing the product of each digit and the corresponding power of 16.
– Hexadecimal digits A-F represent decimal values 10-15.

The decimal point in hexadecimal acts as the separator between positive and negative powers of the base, similar to the decimal point in the decimal system.

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6. Which one of the following is the equivalent 8421BCD code of the decim

Which one of the following is the equivalent 8421BCD code of the decimal number 87.34 ?

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10000111.00110100

10100111.00110100

10001110.11000010

10101110.11000010

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8421 BCD (Binary Coded Decimal) represents each decimal digit by its 4-bit binary equivalent using the weights 8, 4, 2, and 1. To convert the decimal number 87.34 to 8421 BCD, we convert each digit individually:
– Decimal 8: 1000 (8*1 + 4*0 + 2*0 + 1*0 = 8)
– Decimal 7: 0111 (8*0 + 4*1 + 2*1 + 1*1 = 7)
– Decimal point remains the same.
– Decimal 3: 0011 (8*0 + 4*0 + 2*1 + 1*1 = 3)
– Decimal 4: 0100 (8*0 + 4*1 + 2*0 + 1*0 = 4)
Combining these, we get 1000 0111 . 0011 0100. Option A matches this code.

– 8421 BCD represents each decimal digit with its 4-bit binary value.
– The decimal point position is preserved in BCD representation.

BCD is a non-positional system for digits but positional for the number as a whole (e.g., the position of the decimal point matters). While simple for conversion, it is less efficient in terms of storage compared to pure binary representation.

7. Which one of the following technologies is not a touch-screen technolo

Which one of the following technologies is not a touch-screen technology ?

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Resistive technology

Surface technology

Inductive technology

Capacitive technology

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Among the given options, Inductive technology is typically used for stylus input rather than general finger touch-screen operation. Resistive, Surface (e.g., Surface Acoustic Wave – SAW, Surface Capacitive), and Capacitive (e.g., Projective Capacitive) technologies are widely recognized and used as touch-screen methods that respond directly to finger contact (or a conductive object in the case of capacitive). Inductive technology works by sensing an electromagnetic field generated by a specialized stylus interacting with a grid underneath the screen, making it less suitable for passive finger touch.

– Resistive, Surface (SAW, Capacitive), and Capacitive are common touch-screen technologies for finger input.
– Inductive technology primarily relies on electromagnetic resonance with a powered stylus and is not a standard finger-touch technology.

Resistive touch screens work by pressing two layers together. Capacitive touch screens work by sensing the change in capacitance when a conductive object (like a finger) touches the screen. SAW touch screens use ultrasonic waves on the screen surface. Infrared touch screens use infrared beams or imaging.

8. What is the medium used in optical storage systems for reading and rec

What is the medium used in optical storage systems for reading and recording data ?

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High-energy visible light

Laser light

Ultraviolet light

Black light

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Optical storage systems, such as CDs, DVDs, and Blu-ray discs, use a focused beam of light to read and write data on the surface of the disc. This light is typically produced by a laser diode. The laser beam interacts with the data layer on the disc, and changes in the reflected light are detected and interpreted as data (pits and lands representing binary 0s and 1s). For writing, a higher power laser is used to physically alter the data layer.

– Optical storage relies on light to interact with the storage medium.
– Lasers provide the focused, coherent light required for the high data densities and precision needed in optical storage.

The wavelength of the laser light varies depending on the type of optical media. CDs use infrared laser (around 780 nm), DVDs use red laser (around 650 nm), and Blu-ray discs use blue-violet laser (around 405 nm). Shorter wavelengths allow for smaller pits/lands and thus higher storage capacity.

9. In a computer system, which of the following two registers are used by

In a computer system, which of the following two registers are used by the CPU to transfer the data between processor and memory ?

MDR and IR

PC and IR

MAR and MDR

IR and MAR

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The correct answer is C) MAR and MDR.

When the CPU needs to access memory (either to read data/instruction or write data), it uses two primary registers for the transfer:
1. Memory Address Register (MAR): Stores the address of the memory location the CPU wants to access.
2. Memory Data Register (MDR) or Memory Buffer Register (MBR): Temporarily stores the data being read from or written to the memory location specified by the MAR. Data flows between the MDR and the data bus, and between the data bus and memory.

The Instruction Register (IR) holds the current instruction being executed. The Program Counter (PC) holds the address of the *next* instruction. While PC is used to fetch the next instruction (by placing its value in MAR), IR and PC are not the registers directly involved in the data *transfer* between the processor and memory in a general sense; that role is specific to MAR and MDR.

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10. In a computer system, a 32-bit address bus can address

In a computer system, a 32-bit address bus can address

32 memory locations.

232 memory locations.

322 memory locations.

328 memory locations.

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The correct answer is B) 2³² memory locations.

An address bus is used to specify memory locations. The number of bits in the address bus determines the maximum number of unique addresses that the CPU can generate. With an n-bit address bus, there are 2^n possible unique binary combinations, each representing a distinct memory address. Therefore, a 32-bit address bus can address 2^32 memory locations.

In computing, 2^10 is 1 Kilobyte (KB), 2^20 is 1 Megabyte (MB), 2^30 is 1 Gigabyte (GB). So, 2^32 locations would correspond to 4 Gigabytes (4 GB) of addressable memory space (assuming each location is 1 byte). This is a common address space size for 32-bit systems.

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