Most Frequently Asked Infosys Technical Interview Questions And Answers In 2018

Are you keen to join the IT giant Infosys, then this blog post on career guidance, with some common technical interview questions and answers, is just for you.

Commonly asked interview questions and answers:

1. Differentiate between C and C++:

C follows procedural programming pattern while C++ is a multi-paradigm language

C focuses on steps or procedure of the program while C++ focuses on data rather than the process.

In C, data is open while data is secured in C++. This is because of the OOP features like Data Hiding which is absent in C.

C is a low-level language whereas C++ is a middle-level language

C uses top-down approach whereas C++ uses bottom-up approach

C is function-driven and C++ is object-driven

C++ supports function overloading whereas C does not

The NAMESPACE feature in C++ is absent in case of C

2. Define null pointer:

In reference to computer memory, a null pointer is a command to direct a software program or operate a system to an empty location in the computer memory. This is commonly used to denote the end of a memory finding or processing event.

A nil pointer is a false value. E.g. 1 > 2 is a nil statement.

3. What are the 4 basics of OOP?

This is a very common technical interview questions and answers. The 4 basics of OOP are Abstraction, Inheritance, Encapsulation, and Polymorphism.

4. What is Object-Relational DBMS?

An ORD is a database management system like a relational database, and with an object-oriented database model: objects, classes, and inheritance are supported in a database and in the query language.

5. The structural difference between bitmap and b-tree index?


This is made of branch and leaf nodes. Branch nodes hold prefix key value and also the link to the leaf node. The leaf node has the indexed value and rowed.


It has bits for every single distinct value.

6. What is a Database Schema?

This is a set of formulas or sentences called integrity constraints imposed on a database.

7. What are the various levels of database schema?

Conceptual schema- a map of basics and their relationships.

Logical schema- this has entities with features and relations

Physical schema- a specific implementation of a logical schema

Schema object- Oracle database object

8. Tell difference between foreign key and reference key?

Reference Key is a primary key which is referenced in the other table. Foreign Key is how you link the second table to the primary tables Primary Key.

9. Tell me about DSN?

A Data Source Name is the logical name which is used by Open Database Connectivity to refer to the drive and other information which is needed to access data. The name is used by Internet Information Services for a connection to an ODBC data source, like a Microsoft SQL Server database.

10. What are the differences between the Clustered index and non clustered index?

Clustered Index

Only one per table

Fast to read than the non clustered data which is physically stored in index order

Non-Clustered Index

Used several times per table

Quicker for insert and update operations than a clustered index

11. What are WPF and WCF?

WPF or WCF application is needed in .NET 3.0 Framework. This application covers the following concepts:

  • WCF

  • The new service orientated features

  • The usage of interfaces

  • The usage of call-backs

  • Asynchronous delegates

  • Creating the proxy

  • WPF

  • Styles

  • Templates

  • Animations

  • Data binding

  • Multithreading a WPF application

12. What is the difference between an EXE and a DLL?

The term EXE is the acronym for the executable as it identifies a file as a program. And DLL stands for Dynamic Link Library, which has functions and procedures that can be used by other programs.

13. What are the ways to check whether a linked list is circular?

Design two pointers, each set to the beginning of the list. Update each as shown below:

While (pointer1) {

pointer1 = pointer1->next;

pointer2 = pointer2->next; if (pointer2) pointer2=pointer2->next;

If (pointer1 == pointer2) {

Print (“circular\n”);



14. Why is it tough to store linked list in an array?

Both Arrays and Linked List are used to store linear data of similar types.

Linked list give dynamic size while the size of an array is fixed, so you should know the upper limit on the number of elements ahead.

Linked lists have some drawbacks as well:

1) Random access is not allowed.

2) Extra memory space is needed with each list element.

3) Arrays have better cache locality which can create a big difference in performance.

15. Different types of keys in SQL?

The different types of Keys in SQL server are:

A candidate is a unique key. A unique key can be a Primary key. A candidate key is a single column or combination of columns.

Primary Key

To identify a row.

A table permits one Primary key

It is a single column or combination of columns.

Foreign Key

A foreign key is a key that refers to another table’s primary key. A primary key can be referred by several foreign keys from other tables. It is not needed for a primary key to be the reference of any foreign keys.

16. Explain the Joins, Views, Normalization, and Triggers.

The join is used in SQL statement to query data from two or more tables, based on a relationship between certain columns in these tables.

Tables in a database are often related to each other with keys.

A view is a virtual table. A view has rows and columns, like a real table. The fields are fields from one or more real tables in the database.

Normalization is a method to organize data in a database. There is two purpose of normalization process: eliminate the redundant data and ensure data dependencies make sense.

17. Differentiate between socket and session.

The Socket is a mix of IP address and Port Number.

Session is a Logical connection between source and destination

Among the vast resource of questions, we have included a few of the most commonly asked ones.

With this, we conclude with our today’s blog on Infosys interview questions and answers. Hope this piece of information helps you. Keep looking into this space by career advice for more career guidance tips, news, and updates.

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