UP Police Computer Operator flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

OSI model layers

Seven layers from top to bottom: Application, Presentation, Session, Transport, Network, Data Link, Physical. Each layer provides services to the layer above and uses services of the layer below.

TCP vs UDP

TCP is connection-oriented, reliable, and ordered with acknowledgement and retransmission. UDP is connectionless, unreliable, and faster, used for streaming, DNS, and VoIP.

Primary key

A column or set of columns that uniquely identifies each row in a table. It cannot contain NULL values and must be unique for every record.

Normalization 3NF

Third normal form requires the table to be in 2NF and have no transitive dependency: non-key attributes must depend only on the primary key, not on other non-key attributes.

SQL JOIN types

INNER returns matching rows; LEFT returns all left rows plus matches; RIGHT returns all right rows plus matches; FULL returns all rows; CROSS returns the Cartesian product.

Deadlock conditions

Four Coffman conditions must all hold: mutual exclusion, hold and wait, no preemption, and circular wait. Breaking any one condition prevents deadlock.

Virtual memory

A technique that uses secondary storage to extend apparent RAM. Pages are loaded on demand; when RAM is full, page replacement algorithms decide which page to evict.

Absolute vs relative reference

A relative reference like A1 changes when copied. An absolute reference like $A$1 stays fixed. Mixed references like A$1 or $A1 fix only the row or column.

VLOOKUP function

Searches for a value in the first column of a range and returns a value from a specified column in the same row. The fourth argument FALSE or 0 requests an exact match.

Mail merge

A Word feature that combines a main document with a data source to produce personalized letters, labels, or envelopes. Each record in the data source creates one output document.

Two's complement

A method to represent signed integers: invert all bits of the positive number and add 1. An n-bit two's complement ranges from -2^(n-1) to 2^(n-1)-1.

Cache memory

A small, fast SRAM between the CPU and main memory that stores recently used data. L1 is fastest and smallest; L2 and L3 are larger and slower.

Logic gates NAND NOR

NAND outputs 0 only when all inputs are 1. NOR outputs 1 only when all inputs are 0. Both are universal gates because any logic function can be built from either alone.

C pointer

A variable that stores the memory address of another variable. The * operator dereferences it to access the value; the & operator returns a variable's address.

Java main method

The entry point of a Java program: public static void main(String[] args). The JVM calls it without creating an object because it is static.

C switch statement

A multi-way branch that compares an integer or character expression against case labels. A break statement exits the switch; without it, execution falls through to the next case.

CIA triad

Confidentiality ensures data is accessible only to authorized users; integrity ensures data is accurate and unaltered; availability ensures data and services are accessible when needed.

Phishing attack

A social-engineering attack where a fraudulent message, often email or SMS, impersonates a trusted entity to trick the recipient into revealing credentials or clicking malicious links.

IT Act 2000

India's primary cyber law, amended in 2008. It provides legal recognition for electronic records and digital signatures and defines offences such as identity theft and online cheating.

Chain of custody

A documented record of who handled digital evidence, when, and why. It preserves evidence integrity and admissibility in court from collection through analysis and presentation.

UP Police emergency number

Dial 112 for the UP Police emergency response system. National police helpline is 100, fire is 101, and ambulance is 108.

UP Police headquarters

The Uttar Pradesh Police headquarters is located in Lucknow, the state capital. The Director General of Police (DGP) heads the state police force.

UPPRPB

Uttar Pradesh Police Recruitment and Promotion Board, based in Lucknow. It conducts recruitment exams for constable, sub-inspector, and other police posts in the state.

Hindi sandhi

The joining of two sounds or words where the ending vowel of the first meets the beginning of the second. Main types are swar sandhi, vyanjan sandhi, and visarga sandhi.

Active to passive voice

The object becomes the subject, the verb becomes a form of be plus the past participle, and the original subject becomes the by-agent. Example: She writes a letter → A letter is written by her.

Simple interest formula

SI = (P × R × T) / 100, where P is principal, R is annual rate percent, and T is time in years. Total amount = P + SI.

Compound interest formula

A = P(1 + R/100)^T, and CI = A − P. Interest is calculated on the principal plus accumulated interest each period.

Average speed

Average speed = total distance traveled divided by total time taken. It is not the arithmetic mean of the individual speeds unless the times are equal.

DNS

Domain Name System translates human-readable domain names such as example.com into IP addresses. It uses port 53 and a hierarchical distributed database.

DHCP

Dynamic Host Configuration Protocol automatically assigns IP addresses, subnet masks, gateways, and DNS servers to devices on a network. It uses UDP ports 67 and 68.

Access primary key

A field or combination of fields that uniquely identifies each record in an Access table. Access can auto-generate an AutoNumber primary key when a table is created.

PowerPoint Slide Master

A template that controls the design, fonts, colors, and placeholder positions for all slides. Changes to the Slide Master apply to every slide that uses it.