Computer Knowledge - MCQ Practice Questions

INNER JOIN returns only rows with matches in both tables. LEFT JOIN returns all rows from the left table plus matching rows from the right table.

IaaS provides infrastructure resources (compute, storage, networking). SaaS provides applications, PaaS provides development platforms.

Indexes speed up data retrieval by creating optimized lookup structures, reducing the number of disk accesses needed to find data.

Encryption converts data into unreadable format, protecting it from unauthorized access during transmission and storage.

Merge Sort and Quick Sort have O(n log n) average complexity. Merge Sort guarantees this; Quick Sort can degrade to O(n²) in worst case.

The query optimizer analyzes different execution strategies and selects the one with minimal resource consumption and execution time.

Training data is used to teach AI models to recognize patterns. Test data evaluates accuracy; validation data prevents overfitting.

LRU cache requires O(1) access and O(1) removal/insertion of least-used items. Hash Map provides O(1) lookup, and Doubly Linked List maintains order efficiently.

3NF removes transitive dependencies where non-key attributes depend on other non-key attributes. BCNF is stricter but 3NF eliminates transitive dependencies.

Replication maintains copies across nodes for high availability, disaster recovery, and load distribution. It doesn't eliminate backups—they serve different purposes.

Modern languages use Introsort which starts with Quicksort (O(n log n) avg) but switches to Heapsort (O(n log n) worst) to avoid worst-case scenarios.

Overfitting occurs when a model memorizes training data including noise, reducing generalization. Regularization and cross-validation help prevent it.

NoSQL databases prioritize flexible schemas and horizontal scaling. They may use eventual consistency (BASE model) rather than strict ACID.

Sharding partitions data based on a key (e.g., user ID) across servers. This horizontal scaling improves performance and handles large datasets efficiently.

Activation functions (ReLU, Sigmoid, Tanh) add non-linearity, allowing neural networks to learn non-linear relationships. Without them, networks become linear classifiers.

Microservices decompose applications into loosely-coupled, independently deployable services. This enables scalability, flexibility, and technology diversity.

Connection pooling maintains a pool of reusable connections, reducing the cost of opening/closing connections repeatedly. This significantly improves application performance.

Insertion Sort has O(n) best-case complexity for nearly sorted data. Other algorithms don't exploit this, maintaining O(n log n) regardless of initial order.

Least privilege minimizes security risk by restricting access. Users get only permissions needed for their role, reducing damage from compromised accounts.

Relational databases have fixed schemas. Flexible schemas are a characteristic of NoSQL databases like MongoDB.