Low level Design Interview Questions

LLD talks about class diagrams, which show the relationships between the classes, program specifications, and other low-level data of a particular system. Software developers must possess Low-Level Design knowledge to create modular, extendable, and reusable software. This blog post on ‘Low-Level Design Interview Questions and Answers’ discusses real-time questions posed by interviewers across multiple organizations. 

Low-level Design is an ever-expanding field. One can achieve great heights in a career as a system designer by having unique creative skills. So how to clear the Low-Level Designer interview? What other skills are needed to ace the interview process in addition to innovative thinking? To learn more, continue reading.

After consulting with industry-leading experts in the area, the MindMajix team has compiled the often-asked low-level design interview questions in this blog. They are divided into the following sections based on their complexity:

Top 10 Frequently Asked Low-level Design Interview Questions

  1. What exactly is an object-oriented language?
  2. What is UML?
  3. What does "single responsibility" mean?
  4. What benefits do low-level designs offer?
  5. What does the Singleton Design pattern mean?
  6. What is the procedure for creating software?
  7. List a few principles of object-oriented design.
  8. What makes low-level design crucial?
  9. What is LLD System Design?
  10. Can Python be used for LLD?

Low-Level Design Interview Questions for Freshers

1) What benefits and drawbacks do design patterns offer?f

Design patterns are tried-and-true techniques that simplify the software development process and conserve resources. Developers can use previous design patterns to avoid having to fix the same issue repeatedly.

It takes substantial knowledge to use these design patterns. Additionally, established patterns limit creativity and the desire to create novel and improved solutions.

If you want to enrich your career and become a professional in low-level Design, then visit Mindmajix - a global online training platform: " Full Stack Training " This course will help you to achieve excellence in this domain.

2) What exactly is an object-oriented language?

When creating code for software, object-oriented language is necessary. C++, Java, Python, and C# are a few popular programming languages. In order to be considered for low-level design interviews, a candidate must be able to develop object-oriented programming.

3) What is UML?

Unified modeling language, or UML. It is a tool for designing, visualizing, and developing software systems and is not a programming language.

4) What are the principles of object orientation?

The use of object-oriented principles makes the software more adaptable and manageable.

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5) What does "single responsibility" mean?

It implies that there ought to be just one motivation for change within a class. This principle covers each module's function.

  • What differentiates an activity diagram from a sequence diagram?
  • While an activity diagram shows all the cases and flows in a single diagram, a sequence diagram shows the objects to visualize the design flow.
  • While an activity diagram provides a more comprehensive view of the system, a sequence diagram provides an overview of the entire system.
  • The sequence diagram for a movie reservation system shows a controller, manager, and processor for reservations. However, an activity diagram shows every step in detail, from showing a list of movies and theatres to booking seats.

6) What do design patterns imply?

The solutions to some of the issues that arise during the software design process are design patterns. The designing process is sped up by the fact that these have been tried and true.

Related Article: Design Patterns Interview Questions and Answers

7) What benefits do low-level designs offer?

LLD offers a number of benefits.

  • It provides software code with a logical design.
  • It is founded on sophisticated design.
  • It creates class diagrams with relationships between classes and software requirements.
  • The modules are described for simple coding.
  • It creates the software with little testing and debugging.
  • Low cost and maintenance are included.

8) Describe multithreading.

In order to use resources more effectively, a program may be divided into separate jobs or threads, a technique known as multithreading. Multi-threading is possible when the two jobs may be initiated concurrently and are not reliant on one another.

Related Article: Multithreading in Java

9) Name a few design patterns

Behavioral Patterns

Creational Patterns

Structural Patterns

Strategy pattern

Singleton pattern 

Decorator pattern

Observer pattern

Factory pattern

Facade pattern

Observer pattern

Builder pattern

Composite pattern

10) What design patterns are most frequently employed?

Factory,  Singleton, and Strategy are the three design patterns that are most widely employed. They don't demand that you remember the code.

11) What is the procedure for creating software?

The procedure for creating software entails

  • locating the issue at hand
  • collecting demands
  • Specifying high-level elements
  • designing the components with precision
  • writing the program
  • software testing
  • launching the software
  • upkeep of the software

12) What are good coding practices?

  • Use only well-structured codes.
  • Codes must follow high standards.
  • To cut down on errors, complex coding should be avoided. Use only understandable and easy-to-understand coding.
  • Instead of forcing design patterns into the code, concentrate on finding a natural solution to a problem.

 13) What exactly is a code review?

To find errors, enhance code quality, and quicken the software development process, developers evaluate one another's programs. Peer Code Review is another name for it.

 14) What does the Singleton Design pattern mean?

According to this creational design, just one object of a specific class should be created in order to provide global access.

15) Explain the advantages of using SOLID Principles.

SOLID Principles are certain standards to be followed by software developers. They have various advantages

  • They help in identifying faults that lead to bad software designs.
  • They help developers to handle complex designs.
  • They make the code logical and readable.
  • They help the developers to change software without altering the other.

Low-Level Design Interview Questions for Experienced

1) How do you define a strategy pattern?

It indicates that an algorithm or a class's behavior can be modified at run time.

2) How may an LLD problem be resolved?

An LLD problem can be resolved in three steps

Defining and accumulating needs

Understanding the issue and compiling the system's needs and appropriate assumptions is the first stage. Never presume anything.

Use case diagrams and class diagrams

After gathering the requirements, define the classes and objects and ascertain their relationships. To determine the data model, create class diagrams, use case diagrams, and a schema diagram (if necessary).


Quotes can be constructed utilizing design patterns, object-oriented, and SOLID concepts once the structure has been created.

3) List a few principles of object-oriented design.


It features interface segregation, single responsibility, open-closed, Liskov substitution, and dependency inversion.


It implies that you won't require it. It advises adding features just when necessary to cut down on inefficiency.

  • DRY

Don't repeat yourself, it means. It implies that a code shouldn't be used repeatedly. If changes are required, they must also be made in all other locations.

4) Describe how UML diagrams are categorized.

The 14 different varieties of UML diagrams. These are divided into two categories

Behavioral DiagramsStructural Diagrams
These include the system's static view.The system's dynamic view is one of these.
  • Composite structure diagram
  • Component diagram
  • Class diagram
  • Deployment diagram
  • Package diagram
  • Object diagram
  • Profile diagram
  • Timing diagram
  • Communication diagram
  • Interaction overview diagram
  • Activity diagram
  • State machine diagram
  • Sequence diagram
  • Use case Diagram

UML Diagram Types

5) How do you design a reliable traffic light system?

These factors must be taken into account while designing an efficient traffic light system.

  • I'll start by calculating the volume of traffic in the target area, both from vehicles and people.
  • In order to determine how long each light cycle will last, I will also time the pedestrian crossings and traffic flow.
  • I must comprehend how long it takes for cars to pass across a crossing before the light changes in order to configure the timer.
  • Traffic signals must be added while programming in addition to the timer (20-30 seconds between signal changes).
  • The installation of traffic lights should take place in areas where both drivers and pedestrians can see them.

Low-Level Design FAQs

1) What makes low-level design crucial?

Any IT company's core competency is its software. LLD is necessary for the creation of software. Herein lies the value of LLD.

  • LLD creates software data that can alter over time.
  • It considers all specifications and elements required for creating software.
  • It makes implementation and testing easier.
  • It also guarantees that the software will be maintained.

Low-level design interview questions can be a little challenging. Here are some pointers for successfully completing this round:

  • Clearly comprehend the interviewer's query. Don't try to assume anything about yourself.
  • Before continuing, make a list of all the design requirements.
  • When designing, don't rush and take your time.
  • Describe your issues and solutions to the interviewer.

2) What should I expect from a Low-Level Design interview?

Every IT position requires knowledge of low-level design. LLD provides information on software design. Several technical questions on LLD will be asked during the interview. This round may also go by the names pair programming or machine coding. Therefore, it is preferable to comprehend LLD ideas rather than become perplexed by high-level design concerns.

3) What is LLD System Design?

The process of designing software, source codes, data structures, and performance algorithms is known as low-level design.

A High-level design system is transformed into ready-to-code components via LLD.

4) Can Python be used for LLD?

The coding for low-level designing must be written in an object-oriented language. One of the popular object-oriented programming languages is Python.

Tips for Low-Level Design Interview

Here, we have come up with a few tips that will help you overcome any low-level design interview without fear:

  • Call a friend who has experience 

Call a friend who works in this field and ask them about the interview-related questions they have come across. Additionally, search the company to find the most difficult questions. 

  • Be confident and positive

Be confident and positive when you are in front of the interviewer and give your best shot. 

  • Share something outside your CV

The interviewer is aware of your qualifications since they have already seen your CV. When a question like "Tell me about yourself" is directed at you.  Talk about something that isn't on your resume. Explain to the company how your values and principles align with theirs and try to inform the interviewer about your passions outside of work.

  • Give some live examples

When responding, try your best to include some real-world examples. This demonstrates to the interviewer that you are familiar with the subject practically.

  • Be clear with your responses

Any response you give the recruiter should be given in an easily understandable manner. The knowledge that is clearly demonstrated increases the probability of making a favorable impression on recruiters.


I hope this article was able to assist you in getting ready for the low-level design interview. With the help of these questions and responses, you will be better equipped to respond to interviews and do so with assurance.

Apart from this, if you want to get trained by professionals on this technology, you can opt for Full Stack Training from MindMajix!

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Last updated: 14 Apr 2023
About Author


Madhuri is a Senior Content Creator at MindMajix. She has written about a range of different topics on various technologies, which include, Splunk, Tensorflow, Selenium, and CEH. She spends most of her time researching on technology, and startups. Connect with her via LinkedIn and Twitter .

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