Kroll Senior Data Engineer Interview Questions and Answers

Three sections are there 1) Aptitude Test 2) SQL 3) DSA

Q1. What is DSA , sorting , difference between array and linked list
Ans. 
DSA stands for Data Structures and Algorithms. Sorting is the process of arranging data in a particular order. Array is a data structure that stores elements of the same data type in contiguous memory locations, while linked list is a data structure that stores elements in nodes with pointers to the next node.
• DSA stands for Data Structures and Algorithms

• Sorting is the process of arranging data in a particular order

• Arra...read more
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Q2. Written a SQL query
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Q1. Coding question like add numbers
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Q2. Experience on your project
Ans. 
I have experience working on various data analysis projects, including market research, customer segmentation, and predictive modeling.
• Developed predictive models to forecast customer behavior and optimize marketing strategies

• Conducted market research to identify trends and opportunities for growth

• Performed customer segmentation analysis to target specific demographics with personalized marketing campaigns
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Q1. Basics of power bi and sql
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Q2. What are joins and types of join
Ans. 
Joins are used to combine rows from two or more tables based on a related column between them.
• Types of joins include INNER JOIN, LEFT JOIN, RIGHT JOIN, and FULL JOIN

• INNER JOIN returns rows when there is at least one match in both tables

• LEFT JOIN returns all rows from the left table and the matched rows from the right table

• RIGHT JOIN returns all rows from the right table and the matched rows from the left table

• FULL JOIN...read more
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Q3. How to add date table in power bi
Ans. 
To add a date table in Power BI, you can create a new table with a list of dates and relationships with other tables.
• Create a new table in Power BI with a list of dates

• Add columns for day, month, year, etc. for additional analysis

• Establish relationships between the date table and other tables in the data model
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Q1. Sql scenario based question on joins
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Q2. Window function questions
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Q3. Performance tuning
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Q4. Power bi dax question
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Q1. Asked about SAAS, JS questions
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Given a case study need to solve in 2 days

Q1. Explain the case study. Palindrome function in any prog language
Ans. 
A palindrome function checks if a given string reads the same forwards and backwards.
• A palindrome function typically involves reversing the input string and comparing it to the original string.

• Examples: 'racecar' is a palindrome, 'hello' is not a palindrome.

• Common languages for implementing a palindrome function include Python, Java, and C++.
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Q1. General Guidelines
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Q1. How good are you with numbers
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Q1. Vlookup, pivot table, sumif, average, graphs
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Q1. Do you know the role and responsibility of this position
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Q1. .net questions, web api
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Mix of coding, aptitude, java, javascript

Q1. Resume based questions on project
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Q2. Basic SQL, Java streams questions
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Q1. Project related questions
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Q2. Internal working of hashmap
Ans. 
HashMap is a data structure that stores key-value pairs and uses hashing to quickly retrieve values based on keys.
• HashMap internally uses an array of linked lists to store key-value pairs.

• When a key-value pair is added, the key is hashed to determine the index in the array where the pair will be stored.

• If multiple keys hash to the same index, a collision occurs and the pairs are stored in a linked list at that index.

• To...read more
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Q3. Design patterns I've used
Ans. 
I have used design patterns such as Singleton, Factory, and Observer in my projects.
• Singleton pattern ensures a class has only one instance and provides a global point of access to it.

• Factory pattern creates objects without specifying the exact class of object that will be created.

• Observer pattern defines a one-to-many dependency between objects so that when one object changes state, all its dependents are notified and
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Q4. Print whole Fibonacci series using recursion.
Ans. 
Print Fibonacci series using recursion
• Define a recursive function to calculate Fibonacci numbers

• Base case: return 0 if n is 0, return 1 if n is 1

• Recursive case: return sum of previous two Fibonacci numbers

• Print each Fibonacci number in the series
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Q5. Show my Github projects, and the interviewer didn't even properly looked into the code.
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Q1. What are services in Drupal?
Ans. 
Services in Drupal are reusable objects that perform specific functions, such as database queries or sending emails.
• Services are defined in YAML files and can be accessed throughout a Drupal site.

• They are used to encapsulate reusable functionality and promote code reusability.

• Examples of services in Drupal include the database service for interacting with the database, the mail service for sending emails, and the logge
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Q2. How to debug in Drupal?
Ans. 
Debugging in Drupal involves using tools like Devel module, watchdog(), and error logs.
• Enable Devel module for debugging information

• Use watchdog() function to log messages to Drupal's watchdog log

• Check error logs for PHP errors and warnings

• Use dpm() function to print variables for debugging purposes
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Q1. Tell me about yourself
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Q2. Expected salary
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