DHL IT Services Senior Software Engineer Interview Questions and Answers

Q1. Coding question leetcode medium
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Q1. Coding question
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Q2. Leetcode medium
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Q1. Python coding and resume based questions
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Questions are asked from hackerrank . Difficulty level medium .
Prepare for SQL too.

Q1. Your projects, system design
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Q1. What are services in Drupal?
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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?
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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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Write word count program

Q1. Architecture of Spark
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Spark is a distributed computing framework that provides in-memory processing capabilities for big data analytics.
• Spark has a master-slave architecture with a central coordinator called the Spark Master and distributed workers called Spark Workers.

• It uses Resilient Distributed Datasets (RDDs) for fault-tolerant distributed data processing.

• Spark supports various programming languages like Scala, Java, Python, and R for ...read more
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Q2. What is AWS Glue job
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AWS Glue job is a serverless ETL service that makes it easy to prepare and load data for analytics.
• AWS Glue job is used for extracting, transforming, and loading data from various sources into data lakes or data warehouses.

• It allows users to create and run ETL jobs in a fully managed serverless environment.

• AWS Glue job supports various data formats and integrates with other AWS services like S3, Redshift, and RDS.

• Users...read more
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Basic aptitude questions

Linked list, array, tree and graph questions

Q1. Asked to write a program to check whether string is valid or not. String consists of only three kind of special characters "(), [], {}". We need to return true if all special characters are in correct for...read more
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Q2. What is useRef hook used for?
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useRef hook is used to persist a mutable value across renders without causing a re-render.
• Used to store mutable values that do not trigger re-renders.

• Commonly used for accessing DOM elements or storing previous values.

• Does not cause a re-render when the value changes.
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Q3. What are the best practices to avoid rerenders and to improve performance
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Use memoization, virtual DOM, and shouldComponentUpdate to avoid unnecessary rerenders and improve performance.
• Implement memoization to store the result of expensive function calls and avoid recalculating them.

• Use virtual DOM to efficiently update only the parts of the UI that have changed.

• Override shouldComponentUpdate to prevent unnecessary rerenders by comparing current and next props/state.
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Q4. What are callbacks, Promises, async await
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Callbacks, Promises, async await are asynchronous programming concepts in JavaScript.
• Callbacks are functions passed as arguments to another function to be executed later.

• Promises are objects representing the eventual completion or failure of an asynchronous operation.

• async await is a syntax for writing asynchronous code that looks synchronous, making it easier to read and maintain.

• Example: Using a callback to handle th...read more
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