98 questions from 14 interviews · updated from reports 2017-2024
About
Shell is an energy company involved in oil, natural gas, chemicals, power, and retail fuel services. In India, it hires technical talent for roles such as software engineer, associate IT engineer, data engineer, and other IT and digital roles.
The roles that come up most are Software Engineer, Associate IT Engineer and Data Engineer. This covers 14 candidate interviews reported from 2017 to 2024. Most sat it at entry level (12 of 12 that recorded a level). Among the 11 that recorded either route, arrivals split between campus drives (10, 91%) and off-campus applications (1, 9%). Most questions fall under CS fundamentals and Behavioural.
Ans. Class loaders in Java are JVM components that load class bytecode into memory and turn it into Class objects at runtime. The key detail is the parent delegation model: a loader usually asks its parent first, which helps avoid duplicate core classes and supports security, isolation, and custom loading behaviour.
Ans. Reference objects in Java are special objects from java.lang.ref that refer to another object while allowing controlled interaction with garbage collection. The main types are SoftReference, WeakReference, and PhantomReference. They are used for caches, canonical mappings, and cleanup tracking, depending on how strongly the referent should be kept alive.
Ans. The Java garbage collector automatically reclaims heap memory used by objects that are no longer reachable by a running program. It starts from roots such as thread stacks and static references, marks reachable objects, and frees the rest. Most collectors use generational collection because short-lived objects are common, reducing overall overhead.
Ans. SQL databases are relational, schema-based databases that use tables and SQL queries, while NoSQL databases use flexible models such as documents, key-value pairs, graphs or wide columns. SQL is best for structured data and strong consistency. NoSQL is often chosen for scalability, flexible schemas and high-volume distributed data.
Ans. Merge sort divides the array into two halves, recursively sorts each half, then merges the sorted halves into one sorted array. Its time complexity is O(n log n) in the best, average, and worst cases because each level processes all n elements and there are log n levels.
Ans. Design the ETL methodology by defining source to target mappings, profiling data, staging raw extracts, applying transformations in Informatica mappings, and loading curated data through controlled workflows. The most important detail is operational reliability: include parameterisation, incremental loads or CDC, reject handling, audit tables, logging, scheduling, restartability, and reconciliation checks for every run.
Ans. Static loading loads the whole program and required routines into memory before execution starts, while dynamic loading loads a routine only when it is first called. Static loading is simpler but can waste memory. Dynamic loading reduces memory use and supports optional features, but needs runtime support to locate and load code.
Ans. Joins combine rows from two tables based on a related column or condition. An inner join returns only matching rows. Left and right joins keep all rows from one side plus matches from the other. Full outer join keeps all rows from both sides. Cross join returns every pair, and self join joins a table to itself.
Ans. DDL defines database structure, such as CREATE TABLE, ALTER TABLE, and DROP TABLE. DML changes data, such as INSERT, UPDATE, and DELETE. DQL reads data, mainly SELECT. DCL controls permissions, such as GRANT and REVOKE. TCL manages transactions, such as COMMIT, ROLLBACK, and SAVEPOINT. The key distinction is structure, data, access, and transaction control.
Ans. Choose a real situation with clear stakes, ideally involving conflict, pressure, ambiguity, or a mistake. Explain the context briefly, then emphasise your judgement, communication, ownership, and actions. Show how you balanced people, priorities, and business impact. Interviewers listen for self-awareness, calm problem solving, collaboration, and a positive measurable outcome.
Ans. Use a heap of size K and maintain the best K elements seen so far, then sum the heap. For K largest, use a min heap and replace the root when a bigger element appears. For K smallest, use a max heap. This takes O(n log K) time and O(K) space.
Ans. Binary search finds a target in a sorted array by repeatedly checking the middle element and discarding the half that cannot contain the target. Its time complexity is O(log n) because each comparison halves the remaining search space. After k steps, only n divided by 2^k elements remain, so k grows logarithmically.
Ans. C++ stores built-in multidimensional arrays in row-major order, so consecutive elements of the last dimension are contiguous in memory. For int a[3][4], a[0][0], a[0][1], and a[0][2] are adjacent. Pointers store addresses, pointer arithmetic moves by the pointed type size, and arrays often decay to pointers to their first element.
Ans. Yes, memory is consumed, but not for instance fields of that class. When a class is loaded or initialised, the runtime stores class metadata, method information, static fields, constants, and often a Class object. Object-specific memory is only allocated when an instance is actually created.
Ans. Use a SELECT over the required output columns, start from the main table, and JOIN each related table using its foreign key to the matching primary key. Use INNER JOIN when only matching rows are needed, or LEFT JOIN when main-table rows must remain. Add WHERE, GROUP BY, and ORDER BY only if the output requires them.
Ans. Inheritance lets a class reuse and extend behaviour from a parent class. The key benefit is sharing common code while allowing specialised child classes to override or add behaviour. Polymorphism means code can use a parent type while the actual child implementation runs at runtime. Prefer inheritance only for true “is a” relationships.
Ans. My strategy is to model from business use cases and access patterns, then move from conceptual to logical to physical design. I define entities, relationships, constraints, and ownership first, normalise to reduce inconsistency, then denormalise only where performance needs justify it. This is better because it balances correctness, maintainability, and query efficiency.
Ans. Normalize the table by identifying the primary key, attributes, and functional dependencies, then decomposing it into smaller related tables. First ensure 1NF by making values atomic, then 2NF by removing partial dependency on a composite key, then 3NF by removing transitive dependencies. Use foreign keys to preserve relationships and avoid redundancy.
Ans. I would explain the fundamentals behind each listed skill, not just name tools. For example, for classification I would cover train-test split, loss function, overfitting, regularisation, evaluation metrics such as precision and recall, and why a model choice fits the data. The key is connecting concepts to project decisions and trade-offs.
Ans. I start by measuring the slow query with actual execution plans, then reduce the amount of data read before changing anything else. The most important detail is finding expensive scans, joins, sorts, or spills, then fixing them with selective indexes, better predicates, updated statistics, partition pruning, and avoiding unnecessary columns or repeated work.
Ans. JDBC connectivity involves loading the driver, creating a connection, creating a statement, executing a query, processing the result, and closing resources. Important classes and interfaces are DriverManager, Connection, Statement or PreparedStatement, and ResultSet. Key methods include Class.forName, DriverManager.getConnection, createStatement, prepareStatement, executeQuery, executeUpdate, next, and close.
Ans. Choose a real example where you noticed underperformance early and handled it directly but fairly. Emphasise private conversation, listening for causes, clarifying expectations, offering support, and agreeing actions. Show you protected the team’s delivery without blaming. Interviewers listen for maturity, accountability, communication, and willingness to escalate only when needed.
Ans. Use an outer SELECT on the main table with WHERE filters, GROUP BY, HAVING and ORDER BY, and place a subquery in WHERE that itself contains one inner SELECT for related filtering. For example, select customers whose orders include products from a chosen category. With proper indexes, performance is usually logarithmic lookups plus result scanning.
Ans. Advanced SQL and DBMS theory focuses on correct data modelling, reliable transactions, and efficient querying. Key points are normal forms to reduce redundancy, relations defined by keys and constraints, ACID transactions with isolation levels, ER models mapped to tables, and complex queries using joins, subqueries, grouping, window functions, and indexes.
Ans. Find any array element whose frequency is exactly K. Subtracting the same element from every array value only shifts all values, so equal elements remain equal and unequal elements remain unequal. Count frequencies with a hash map, then return an element with count K. Time complexity is O(n), space is O(n).
Ans. Pick a real project where the obstacle was significant but solvable through your actions. Emphasise how you assessed the issue, involved the right people, adjusted the plan, and kept delivery moving. Interviewers listen for ownership, calm problem solving, communication, prioritisation, and learning, not blame or drama.
Ans. Process the array from left to right and maintain counts of previous values in a Fenwick tree or balanced order-statistic tree. For each element x, compute how many previous elements are less than or equal to x, then subtract from the number processed so far. Use coordinate compression. Time complexity is O(n log n).
Ans. The answer is one main component plus every isolated prime greater than (N+1)/2. For N=10, the main group is {2,3,4,5,6,8,9,10}, and 7 and 11 are isolated, so the output is 3. Use a sieve to count those primes in O(N log log N).
Ans. Yes, I have worked with relational databases such as PostgreSQL and MySQL, and some NoSQL stores. I have designed tables, written queries, added indexes, and handled transactions. The most important part has been understanding access patterns so the schema and indexes support fast, reliable reads and writes.
Ans. Common JavaScript frameworks include Angular, Vue.js, Svelte, Ember.js, Next.js and Nuxt. Angular is a full front-end framework, while Next.js and Nuxt add server-side rendering and routing on top of React and Vue respectively. React is often mentioned too, although it is technically a UI library.
Ans. SQL joins combine rows from two tables using a related column, usually a primary key and foreign key. The main types are INNER JOIN, which returns matching rows only; LEFT JOIN and RIGHT JOIN, which keep all rows from one side; FULL OUTER JOIN, which keeps all rows; and CROSS JOIN, which returns every combination.
Ans. An immutable class in Java is a class whose object state cannot be changed after construction. Its fields are usually private and final, it provides no setters, and it does not expose mutable internal objects directly. For mutable fields, use defensive copies in the constructor and getters. String is a common example.
Ans. Python is a high-level, interpreted, dynamically typed language known for readable syntax, rapid development, and a large standard library. Key features include automatic memory management, object-oriented and functional programming support, portability across platforms, extensive third-party packages, and strong community support. Its simplicity makes it popular for scripting, web development, data science, and automation.
Ans. Interfaces in Java define a contract that classes can implement, specifying what methods are available without fixing how they work. They are mainly used for abstraction and polymorphism, letting code depend on a common type rather than a specific class. Java also uses interfaces to support multiple inheritance of type.
Ans. Neither is universally better; AWS is usually stronger for breadth and maturity, while Azure is often better for organisations already invested in Microsoft. The key factor is fit: existing skills, integrations, compliance needs, pricing, and managed services. In practice, choose the platform that reduces operational risk and total cost for the specific workload.
Ans. Java Database Connectivity, or JDBC, is Java’s standard API for connecting to and working with relational databases. It lets Java applications send SQL queries, update data, and read results in a database-independent way, using JDBC drivers that translate the standard API calls for a specific database system.
Ans. No, not in the same usual sense. Java source is compiled to JVM bytecode, then typically run with just-in-time compilation. Python source is usually compiled automatically to bytecode and executed by an interpreter. So both involve compilation, but Java is normally described as compiled, while Python is normally described as interpreted.
Ans. SQL is a standard language used to query and manage relational databases, while MySQL is a specific relational database management system that uses SQL. SQL defines commands such as SELECT, INSERT and UPDATE. MySQL is the software that stores data, runs those commands, manages users, indexes, transactions and connections.
Ans. The load factor of a HashMap in Java is the ratio of stored entries to the number of buckets. It controls when the map is resized. The default load factor is 0.75, meaning the HashMap grows when it is 75% full, balancing memory use and lookup performance.
Ans. JVM runs Java bytecode, JRE provides the JVM plus libraries needed to run Java programs, and JDK provides the JRE plus tools to develop them. Use the JRE to run applications, the JDK to compile and debug them. The JVM is the platform-specific engine that makes Java bytecode portable.
Ans. Database triggers are stored procedures that run automatically when events such as insert, update or delete occur on a table. ACID properties define reliable transactions: atomicity means all or nothing, consistency preserves rules, isolation prevents interference between transactions, and durability ensures committed changes survive failures. Triggers should be used carefully to avoid hidden side effects.
Ans. static means a member belongs to the class rather than to each object, so it is accessed through the class and shared by all instances. final means something cannot be changed in its relevant sense: a variable cannot be reassigned, a method cannot be overridden, and a class cannot be extended.
Ans. Java does not support pointers in the C or C++ sense. It has references to objects, which let you access objects indirectly, but you cannot see memory addresses, do pointer arithmetic, or manually free memory. This improves safety, while memory management is handled by the JVM and garbage collector.
Ans. Commonly used data structures include arrays, linked lists, stacks, queues, hash tables, trees, heaps and graphs. The key detail is choosing based on access, insertion, deletion and search costs: arrays give fast indexing, hash tables give average constant-time lookup, trees keep data ordered, and graphs model relationships.
Ans. HashMap in Java stores key-value pairs for fast insertion, lookup, update and deletion by key. It is commonly used for caching, indexing objects by ID, counting frequencies, grouping data, and removing duplicates. Operations are average constant time, but it does not preserve order and is not thread-safe.
Ans. SQL databases store structured data in tables with fixed schemas and use SQL for relational queries. NoSQL databases use more flexible models such as documents, key value pairs, columns, or graphs. The key difference is that SQL favours strong consistency and complex joins, while NoSQL often favours flexibility, scale, and high availability.
Ans. Python is a general-purpose programming language, and it is also commonly used as a scripting language. The important point is that “scripting” describes how it is often used, for automation and glue code, not a limitation of the language. Python supports full application development, object-oriented programming, libraries, and large systems.
Ans. Method overloading means defining multiple methods with the same name but different parameter lists in the same class, while method overriding means a subclass provides a new implementation of a method already defined in its superclass. Overloading is resolved at compile time; overriding is resolved at runtime through dynamic dispatch.
Ans. Draw a clear diagram or table first. For arrangements, place fixed positions, then apply clues one by one, marking definite, possible and impossible positions. For pie charts, convert percentages or angles into values using the total. Compare only like units, check totals, and verify the final answer against every condition.
Ans. I have used Linux daily to build and operate data pipelines, mainly through shell scripting, cron, SSH, file permissions, log inspection, and process monitoring. The most important detail is being comfortable debugging failures from the command line, using tools like grep, awk, tail, df, top, and system logs to find issues quickly.
Ans. No, a non-static variable cannot be accessed directly by a static method in Java. A static method belongs to the class, while a non-static variable belongs to an object instance. To access it, the static method must use a reference to an object of that class.
Ans. Yes, I have used both shell scripting and Python in ETL workflows. Shell scripts were useful for scheduling, file movement, validation checks and calling batch jobs, while Python was better for parsing, transformations, API extraction and error handling. I usually add logging, retries and row count checks to make the workflow reliable.
Ans. Neither is always better; choose the approach that makes the solution clearest and safest for the problem. Recursion is natural for trees, divide and conquer, and backtracking, but it uses call stack space and can overflow. Iteration is usually more memory efficient and often easier to control for simple loops.
Ans. Keys identify rows, normalization reduces redundancy, transactions keep changes reliable, and joins combine related tables. A primary key is unique and not null, while a foreign key references another table. Normal forms organise data to avoid update anomalies. Transactions follow ACID properties. Inner, left, right and full joins differ in unmatched row handling.
Ans. Method overloading means defining multiple methods with the same name but different parameter lists in the same class, while method overriding means a subclass provides its own implementation of a method already defined in its parent class. Overloading is resolved at compile time, whereas overriding is resolved at runtime using dynamic dispatch.
Ans. Choose a recent example where Agile improved delivery, not just where ceremonies existed. Emphasise your role in planning, prioritisation, stand-ups, reviews, retrospectives, managing blockers, and adapting to change. Interviewers listen for collaboration, transparency, customer focus, incremental delivery, and evidence that you helped the team improve outcomes.
Ans. Convert every statement into an equation using a clear variable. For percentages, write percent as a fraction or decimal and identify the base value. For ages, form present age variables and add or subtract years consistently. For profit and loss, use cost price, selling price, profit percent, and loss percent formulas, then solve step by step.
Ans. Scan the string once and increment a counter whenever the current character is 'A'. Use a simple integer variable to store the count, as no extra data structure is needed. This approach checks every character exactly once, so the time complexity is O(n) and the space complexity is O(1).
Ans. Identify the topic first, such as percentages, ratios, time and work, probability, series, coding, or seating. Write the given data clearly, convert words into equations or diagrams, and solve step by step. Use shortcuts only after understanding the logic. Check units, options, and edge cases before choosing the answer.
Ans. Object-Oriented Programming organises software around objects that combine data and behaviour. A class is a blueprint, and an object is an instance of it. The main concepts are encapsulation to hide internal state, abstraction to expose essentials, inheritance to reuse and extend behaviour, and polymorphism to use one interface with different implementations.
No question matches those filters. Reset filters.
Showing 60 of 98 questions. Ranked by how often the same question came back across interviews.
A spoken interview built from these questions, scored when you finish; the feedback is yours.
Start practisingWhen you are ready, record The One: a single interview hiring teams watch, so you stop repeating first rounds.
Candidate interviews most often cover CS fundamentals (60%) and Behavioural (21%).
Candidate interviews show an average of 2.2 rounds per experience, with a typical sequence of Online test → Technical. Individual interview paths can vary.
Among questions with a recorded difficulty, the mix is easy 59%, medium 40%, hard 1%.
