Deloitte Interview Questions and Answers for Technical Profiles

Deloitte is a leading global professional services firm with over 345,000 employees in more than 150 countries. The company offers a variety of technical roles in areas such as software engineering, data science, and IT infrastructure.

When preparing for a technical interview at Deloitte, it’s important to be ready for challenging questions. To increase your chances of success, this article provides a comprehensive list of common Deloitte technical interview questions and detailed answers. These questions cover topics like Object-Oriented Programming (OOP), Java, C++, and Database Management Systems (DBMS). Reviewing this information will give you a better idea of what to expect and help you be well-prepared to answer any questions your interviewer may ask.

Here in this article, we listed a few popular questions and answers that have been asked in the Deloitte for Technical Profiles.

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1. What is a Thread?
A thread is a single sequence stream within a process. Because threads have some of the properties of processes, they are sometimes called lightweight processes. Threads are a popular way to improve the application through parallelism. For example, in a browser, multiple tabs can be different threads. MS Word uses multiple threads, one thread to format the text, another thread to process inputs, etc. 

2. What are the differences between process and thread?
A thread has its own program counter (PC), a register set, and a stack space. Threads are not independent of one another, like processes. As a result, threads share with other threads their code section, data section, and OS resources like open files and signals.

3. What is a kernel?
A kernel is the central component of an operating system that manages the operations of computers and hardware. It basically manages operations of memory and CPU time. It is a core component of an operating system. Kernel acts as a bridge between applications and data processing performed at the hardware level using inter-process communication and system calls.

4. What is Banker’s algorithm?
The banker’s algorithm is a resource allocation and deadlock avoidance algorithm that tests for safety by simulating the allocation for the predetermined maximum possible amounts of all resources, then makes an “s-state” check to test for possible activities, before deciding whether allocation should be allowed to continue.

5. What is the difference between the Operating system and kernel?

Operating System	Kernel
Operating System is system software.	The kernel is system software that is part of the Microkerneloperating system.
The Operating System provides an interface b/w the user and the hardware.	The kernel provides an interface b/w the application and hardware.
It also provides protection and security.	Its main type purpose is memory management, disk management, process management, and task management.
All system needs a real-time operating real-time, and Microkernel system to run.	All operating system needs a kernel to run.
Type of operating system includes single and multiuser OS, multiprocessor OS, real-time OS, and Distributed OS.	Type of kernel includes Monolithic and Microkernel.

6. Write a difference between process and program.

ProgramThe type	Process
The program contains a set of instructions designed to complete a specific task.	The process is an instance of an executing program.
A program is a passive entity as it resides in the secondary memory.	The process is a process active entity as it is created during execution and loaded into the main memory.
The program exists in a single place and continues to exist until it is deleted.	The process exists for a limited span of time as it gets terminated after the completion of a task.
A program is a static entity.	The process is a dynamic entity.
The program does not have any control block.	The process has its own control block called the Process Control Block.

7. What are the advantages of multithreading?

• Improved throughput. Many concurrent compute operations and I/O requests within a single process.
• Simultaneous and fully symmetric use of multiple processors for computation and I/O.
• Minimized system resource usage. Threads impose minimal impact on system resources. Threads require less overhead to create, maintain, and manage than a traditional process.

8. What is the difference between paging and segmentation?

Paging	Segmentation
Page size is determined by hardware.	Here, the section size is given by the user.
It is faster in comparison to segmentation.	Segmentation is slow.
A page table is employed to keep up the page data.	Section Table maintains the section data.
Paging is invisible to the user.	Segmentation is visible to the user.
Paging could result in internal fragmentation.	Segmentation could result in external fragmentation.

9. What are tokens in C?

• Keywords
• Constants
• Strings
• Operators
• Constants

10. What are preprocessor directives in C?
In C preprocessor directives are considered the built-in predefined functions or macros that act as a directive to the compiler and are executed before the program execution. There are multiple steps involved in writing and executing a program in C.

11. What is the difference between malloc() and calloc() in the C programming language?

Parameter	Malloc()	Calloc()
Definition	It is a function that creates one block of memory of a fixed size.	It is a function that assigns more than one block of memory to a single variable.
Number of arguments	It only takes one argument.	It takes two arguments.
Speed	malloc() function is faster than calloc().	calloc() is slower than malloc().
Efficiency	It has high time efficiency.	It has low time efficiency.
Usage	It is used to indicate memory allocation.	It is used to indicate contiguous memory allocation.

12. What is recursion
Recursion is the process of making the function call itself directly or indirectly. A recursive function solves a particular problem by calling a copy of itself and solving smaller subproblems that sum up the original problems. 

13. What is the difference between a while loop and a do-while loop?

While Loop	do-while Loop
While loop is also termed an entry-controlled loop	The do-while loop is termed an exit control loop
If the condition is not satisfied the statements inside the loop will not execute	Even if the  condition is not satisfied the statements inside the loop will execute for at least one time
Example of a while loop: while(condition)  {statements to be executed;};	Example of a do-while loop: do { statements to be executed; } while(condition or expression);

14. What is Function Overriding?
When a function of the same name, the same arguments or parameters, and the same return type already present/declared in the base class is used in a derived class is known as Function Overriding. It is an example of Runtime Polymorphism or Late Binding which means the overridden function will be executed at the run time of the execution.

15. Operator Overloading in C++
In C++, we can make operators work for user-defined classes. This means C++ has the ability to provide the operators with a special meaning for a data type, this ability is known as operator overloading. For example, we can overload an operator ‘+’ in a class like String so that we can concatenate two strings by just using +. Other example classes where arithmetic operators may be overloaded are Complex Numbers, Fractional Numbers, Big integers, etc.

16. What are the various OOP concepts in C++?

• Classes: It is a user-defined datatype
• Objects: It is an instance of a class
• Abstraction: It is a technique of showing only necessary details
• Encapsulation: Wrapping of data in a single unit
• Inheritance: The capability of a class to derive properties and characteristics from another class
• Polymorphism: Polymorphism is known as many forms of the same thing

17. What is the class and object in C++?

• Class: A Class is a user-defined data type that has data members and member functions.
• Object: An Object is an identifiable entity with some characteristics and behavior. An Object is an instance of a Class. 

18. What is the inheritance and types of inheritance in C++
The capability or ability of a class to derive properties and characteristics from another class is known as inheritance. In simple terms, it is a system or technique of reusing and extending existing classes without modifying them.

• Single inheritance: In single inheritance, a class is allowed to inherit from only one class. i.e. one subclass is inherited by one base class only.
• Multiple inheritance: Multiple Inheritance is a feature of C++ where a class can inherit from more than one class. i.e. one subclass is inherited from more than one base class.
• Hierarchical inheritance: In this type of inheritance, more than one subclass is inherited from a single base class. i.e. more than one derived class is created from a single base class.
• Multilevel inheritance: In this type of inheritance, a derived class is created from another derived class.
• Hybrid inheritance:  Hybrid Inheritance is implemented by combining more than one type of inheritance. For example: Combining Hierarchical inheritance and Multiple Inheritance. 

19. Polymorphism in C++
The word “polymorphism” means having many forms. In simple words, we can define polymorphism as the ability of a message to be displayed in more than one form. 

Types of Polymorphism

• Compile-time Polymorphism: This type of polymorphism is achieved by function overloading or operator overloading.
  • Function Overloading
  • Operator Overloading
• Runtime Polymorphism: This type of polymorphism is achieved by Function Overriding. Late binding and dynamic polymorphism are other names for runtime polymorphism.
  •  Function Overriding
  • Virtual Function

20. Difference between Prefix and Postfix?

• Prefix: Operators are placed before the corresponding operands in the expression.
• Postfix: Operators are placed after the corresponding operands in the expression.     

21. What is Pointer?
A pointer can be used to store the memory address of other variables, functions, or even other pointers. 

Syntax:

datatype * ptr;

Pointer Declaration

int *ptr;

Types of Pointers 

• Integer Pointers
• Array Pointer
• Structure Pointer
• Function Pointers
• Double Pointers
• NULL Pointer
• Void Pointer
• Wild Pointers
• Constant Pointers
• Pointer to Constant

22. Difference Between Call by Value and Call by Reference

Call By Value	Call By Reference
While calling a function, we pass the values of variables to it. Such functions are known as “Call By Values”.	While calling a function, instead of passing the values of variables, we pass the address of variables(location of variables) to the function known as “Call By References.
In this method, the value of each variable in the calling function is copied into corresponding dummy variables of the called function.	In this method, the address of actual variables in the calling function is copied into the dummy variables of the called function.
With this method, the changes made to the dummy variables in the called function have no effect on the values of actual variables in the calling function.	With this method, using addresses we would have access to the actual variables and hence we would be able to manipulate them.
In call-by-values, we cannot alter the values of actual variables through function calls.	In call by reference, we can alter the values of variables through function calls.

23. What are super, primary, candidate, and foreign keys? 

• A super key is a set of attributes of a relation schema upon which all attributes of the schema are functionally dependent. No two rows can have the same value of super key attributes. 
• A Candidate key is a minimal superkey, i.e., no proper subset of Candidate key attributes can be a superkey. 
• A Primary Key is one of the candidate keys. One of the candidate keys is selected as the most important and becomes the primary key. There cannot be more than one primary key in a table..
• A Foreign key is a field (or collection of fields) in one table that uniquely identifies a row of another table. 

24. What is database normalization? 
It is a process of analyzing the given relation schemas based on their functional dependencies and primary keys to achieve the following desirable properties: 

• Minimizing Redundancy 
• Minimizing the Insertion, Deletion, And Update Anomalies Relation schemas that do not meet the properties are decomposed into smaller relation schemas that could meet desirable properties. 

25. What are the differences between DDL, DML, and DCL in SQL? 
Following are some details of three :

• DDL stands for Data Definition Language. SQL queries like CREATE, ALTER, DROP, TRUNCATE, and RENAME come under this. 
• DML stands for Data Manipulation Language. SQL queries like SELECT, INSERT, DELETE, and UPDATE come under this. \
• DCL stands for Data Control Language. SQL queries like GRANT and REVOKE come under this. 

26. ACID Properties
A transaction is a single logical unit of work that accesses and possibly modifies the contents of a database. Transactions access data using read-and-write operations. 
In order to maintain consistency in a database, before and after the transaction, certain properties are followed. These are called ACID properties. 

27. What are the layers in the OSI model?
There are a total of 7 layers

• Physical Layer
• Data Link Layer
• Network Layer
• Transport Layer
• Session Layer
• Presentation Layer
• Application Layer

28. Explain LAN (Local Area Network)
LAN or Local Area Network connects network devices in such a way that personal computers and workstations can share data, tools, and programs. The group of computers and devices are connected together by a switch, or stack of switches, using a private addressing scheme as defined by the TCP/IP protocol.

29. Types of Network Topology
In Computer Networks, there are various ways through which different components are connected to one another. Network Topology is the way that defines the structure, and how these components are connected to each other.

Types of Network Topology

The arrangement of a network that comprises nodes and connecting lines via sender and receiver is referred to as Network Topology. The various network topologies are:

• Point to Point-to-Point topology
• Mesh Topology
• Star Topology
• Bus Topology
• Ring Topology
• Tree Topology
• Hybrid Topology

30. In which OSI layer is the header and trailer added?
At the Data link layer trailer is added and at the OSI model layer 6,5,4,3 added header.

31. What is a VPN?
VPN stands for the virtual private network. A virtual private network (VPN) is a technology that creates a safe and encrypted connection over a less secure network, such as the Internet. A Virtual Private Network is a way to extend a private network using a public network such as the Internet.

32. What is IP Spoofing?
IP Spoofing is essentially a technique used by hackers to gain unauthorized access to Computers. Concepts of IP Spoofing were initially discussed in academic circles as early as 1980. IP Spoofing types of attacks have been known to Security experts on the theoretical level.

33. What are the Advantages of Fiber Optics?
The advantages of Fiber Optics are mentioned below:

• Bandwidth is above copper cables.
• Less power loss and allows data transmission for extended distances.
• The optical cable is resistant to electromagnetic interference.
• Fiber cable is sized 4.5 times which is better than copper wires.
• As the cable is lighter, and thinner, in order that they use less area as compared to copper wires.

33. Name two technologies by which you would connect two offices in remote locations.
Two technologies that would connect two offices in remote locations are VPN and Cloud computing.

34. Name the hardware layers or network support layers in the OSI model.

• Network layer
• Datalink layer
• Physical layer

35. Define HTTPS protocol
The full form of HTTPS is a Hypertext transfer protocol secure. It is an advanced version of the HTTP protocol. Its port number is 443 by default. It uses SSL/TLS protocol for providing security.

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