Cognizant
20+ Epinet Info Interview Questions and Answers
Q1. Briefly explain the method you will use to execute an array linked list?
An array linked list can be executed using a loop to traverse through the array and access the linked nodes.
Create an array to store the linked nodes
Assign the first node to the first element of the array
Use a loop to traverse through the array and access the linked nodes
To access the next node, use the index of the current node as the index of the next node in the array
Stop the loop when the last node is reached
Q2. What is the difference between primary key, foreign key, candidate key & super key?
Primary key uniquely identifies a record, foreign key links tables, candidate key can be primary key, super key is a set of attributes.
Primary key: Unique identifier for a record in a table
Foreign key: Links tables together by referencing the primary key of another table
Candidate key: A set of attributes that can be used as a primary key
Super key: A set of attributes that can uniquely identify a record
Q3. What are streams in C++? What are predefined streams in C++?
Streams in C++ are used for input and output operations. Predefined streams in C++ include cin, cout, cerr, and clog.
Streams in C++ are objects that allow reading from or writing to external sources or destinations.
cin is the standard input stream used for reading input from the user.
cout is the standard output stream used for printing output to the console.
cerr is the standard error stream used for printing error messages to the console.
clog is an alternative to cerr for pri...read more
Q4. What are reference variables and how is it defined in C++?
Reference variables in C++ are aliases for other variables, allowing direct access and manipulation of the original data.
Reference variables are declared using an ampersand (&) symbol.
They must be initialized when declared and cannot be reassigned to refer to a different variable.
Changes made to a reference variable affect the original variable it refers to.
They are commonly used to pass variables by reference to functions.
Reference variables can be used to create multiple na...read more
Q5. Can you tell us something about scope rules in C++?
Scope rules in C++ determine the visibility and accessibility of variables and functions within a program.
Variables declared within a block have local scope and are only accessible within that block.
Global variables have file scope and can be accessed from any function within the file.
Function parameters have function scope and are only accessible within that function.
Nested blocks can have their own scope, and variables declared within them are only accessible within that bl...read more
Q6. What is the difference between a "semaphore" and a "monitor"?
Semaphore and monitor are synchronization tools used in concurrent programming.
Semaphore is a signaling mechanism that allows multiple threads to access a shared resource simultaneously.
Monitor is a synchronization construct that allows threads to have both mutual exclusion and the ability to wait (block) for a certain condition to become true.
Semaphore is a lower-level primitive, while monitor is a higher-level abstraction.
Semaphore can be used to implement a monitor.
Example...read more
Q7. Do you think BCNF is better than 2NF & 3NF? Why?
BCNF is not necessarily better than 2NF & 3NF, it depends on the specific requirements of the database.
BCNF is the highest normal form and ensures that there are no non-trivial functional dependencies between any subset of candidate keys.
2NF and 3NF are also important and should be used when appropriate.
For example, if a database has a composite primary key and non-key attributes that depend on only one part of the key, 2NF should be used.
If a database has transitive dependen...read more
Q8. What are the various forms of normalisation?
Normalization is a process of organizing data in a database to eliminate redundancy and improve data integrity.
First Normal Form (1NF) - Eliminate duplicate data by separating them into multiple tables.
Second Normal Form (2NF) - Remove partial dependencies by creating separate tables for sets of attributes.
Third Normal Form (3NF) - Eliminate transitive dependencies by creating separate tables for related attributes.
Boyce-Codd Normal Form (BCNF) - Remove anomalies by ensuring ...read more
Q9. What is difference between rand() and srand()?
rand() generates a random number, srand() seeds the random number generator.
rand() generates a pseudo-random number between 0 and RAND_MAX
srand() sets the seed for the random number generator used by rand()
srand() should be called before rand() to ensure different sequences of random numbers
Example: srand(time(NULL)) sets the seed to the current time, ensuring a different sequence each time the program is run
Q10. What is the "top-n analysis" in DBMS?
Top-n analysis is a technique used in DBMS to retrieve the top n records based on a specific criteria.
Used to retrieve top n records
Based on specific criteria
Commonly used in data analysis and reporting
Q11. What are character constants in C++?
Character constants are fixed values represented by a single character in C++.
They are enclosed in single quotes (' ')
Examples include 'a', 'B', '5', '$'
They are also known as character literals
Q12. What do you mean by normalisation?
Normalisation is the process of organizing data in a database to reduce redundancy and improve data integrity.
It involves breaking down a table into smaller tables and defining relationships between them.
Normalization helps to eliminate data inconsistencies and anomalies.
There are different levels of normalization, with each level having specific rules to follow.
Examples of normalization include converting repeating groups into separate tables and creating a junction table fo...read more
Q13. Where do we generally create INDEX?
INDEX is generally created on columns that are frequently used in WHERE, JOIN, and ORDER BY clauses.
INDEX improves the performance of SELECT queries.
INDEX should be created on columns with high selectivity.
INDEX should not be created on columns with low selectivity.
Examples of columns to create INDEX on are primary keys, foreign keys, and columns used in search queries.
Q14. Differentiate exclusive lock and shared lock.
Exclusive lock is used when a resource is being modified and prevents other processes from accessing it. Shared lock allows multiple processes to read a resource simultaneously.
Exclusive lock is used for write operations, while shared lock is used for read operations.
Exclusive lock blocks other processes from acquiring both exclusive and shared locks on the same resource.
Shared lock allows multiple processes to acquire shared locks on the same resource simultaneously.
Exclusiv...read more
Q15. Explain these terms - Linked List, Stack, Queue.
Linked List is a linear data structure. Stack and Queue are abstract data types.
Linked List: A collection of nodes where each node points to the next node.
Stack: A data structure where elements are added and removed from the top only.
Queue: A data structure where elements are added at the rear and removed from the front only.
Example: Browser history can be implemented using a Linked List.
Example: Undo/Redo functionality can be implemented using a Stack.
Example: Print queue ca...read more
Q16. What is object oriented model?
Object oriented model is a programming paradigm that uses objects to represent real-world entities.
Objects have properties and methods that define their behavior
Encapsulation, inheritance, and polymorphism are key concepts in OOP
Examples of OOP languages include Java, C++, and Python
Q17. Define the terms OSI, TCP & IP.
OSI, TCP & IP are networking protocols used for communication between devices on a network.
OSI (Open Systems Interconnection) is a conceptual model that defines how data is transmitted over a network.
TCP (Transmission Control Protocol) is a protocol that ensures reliable transmission of data between devices.
IP (Internet Protocol) is a protocol that handles the addressing and routing of data packets between devices on a network.
TCP/IP is a suite of protocols that are commonly ...read more
Q18. What is Operating System?
An operating system is a software that manages computer hardware and software resources.
It acts as an interface between the user and the computer hardware.
It provides services to applications and manages system resources.
Examples include Windows, macOS, Linux, Android, and iOS.
Q19. What is RDBMS KERNEL?
RDBMS KERNEL is not a commonly used term in the industry.
There is no widely accepted definition of RDBMS KERNEL.
It may refer to the core components of a relational database management system.
It could also be a term used by a specific company or product.
Without more context, it is difficult to provide a specific answer.
Q20. Define triggers. Give its applications.
Triggers are events that initiate an action or set of actions. They are commonly used in databases and automation systems.
Triggers are used in databases to automatically execute a set of actions when a certain event occurs, such as inserting or updating data.
They can also be used in automation systems to initiate a process or workflow when a specific event occurs, such as receiving an email or a file upload.
Triggers can be programmed to perform a variety of actions, such as s...read more
Q21. Why is DML provided?
DML is provided to manipulate data in a database.
DML stands for Data Manipulation Language.
It is used to insert, update, delete, and retrieve data from a database.
DML commands include INSERT, UPDATE, DELETE, and SELECT.
DML is essential for managing and maintaining data in a database.
Q22. Diff. Between promise and observable
Promise is a one-time event while Observable can emit multiple values over time.
Promise is used for asynchronous operations that will return a single value or an error.
Observable is used for asynchronous operations that can return multiple values over time.
Promise can be in one of three states: pending, fulfilled, or rejected.
Observable can emit values, errors, and completion events.
Promise can be converted to an Observable using the from() method in RxJS.
Observable can be co...read more
Q23. Differentiate RDBMS and DBMS.
RDBMS is a type of DBMS that stores data in a structured manner using tables with relationships.
RDBMS stands for Relational Database Management System
Data is stored in tables with predefined relationships
Data is accessed using SQL (Structured Query Language)
Examples include MySQL, Oracle, and SQL Server
DBMS is a broader term that includes all types of database management systems
Examples of DBMS include MongoDB, Cassandra, and Redis
Q24. Jwt security implementation in angular
Jwt security implementation in Angular
Install angular-jwt package
Create an auth service to handle token storage and retrieval
Add an HttpInterceptor to attach the token to outgoing requests
Use guards to protect routes based on authentication status
Q25. Discuss transparent DBMS.
Transparent DBMS allows users to see and control the underlying database operations.
Transparent DBMS provides visibility into the database operations and allows users to monitor and control them.
It enables users to see how data is being stored, accessed, and manipulated in real-time.
Examples include Oracle Transparent Data Encryption and Microsoft SQL Server Transparent Data Encryption.
Transparent DBMS can improve security, performance, and compliance with regulations.
Q26. Define RDBMS.
RDBMS stands for Relational Database Management System.
It is a type of database management system that stores data in tables with relationships between them.
It uses SQL (Structured Query Language) to manipulate and retrieve data.
Examples include MySQL, Oracle, and Microsoft SQL Server.
Q27. Define subquery.
A subquery is a query within another query used to retrieve data that will be used in the main query.
Subqueries are enclosed in parentheses and placed within the WHERE clause of the main query.
They can be used to filter results based on a condition that involves data from another table.
Subqueries can also be used in the SELECT, FROM, and HAVING clauses.
Examples include finding the average salary of employees in a department or selecting the top 5 customers based on their tota...read more
Q28. Lifecycle hooks in angular
Angular lifecycle hooks are methods that get called at specific stages of a component's lifecycle.
ngOnInit() - called after the component is initialized
ngOnChanges() - called when the component's input properties change
ngOnDestroy() - called just before the component is destroyed
ngAfterViewInit() - called after the component's view has been initialized
ngAfterContentInit() - called after the component's content has been initialized
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