NoSQL databases offer schema flexibility, allowing developers to store and manage unstructured or semi-structured data without predefined schemas. This flexibility is advantageous in scenarios where the data model is evolving or where dealing with highly variable data types. Unlike traditional relational databases that enforce a strict schema, NoSQL databases can adapt to changing data requirements, making them more scalable and agile in certain use cases.

SFTP (SSH File Transfer Protocol) is recommended for secure file transfers because it encrypts both authentication information and data being transferred. This ensures that sensitive files are protected from unauthorized access during transmission. FTPS also provides secure file transfer, but it requires additional configurations such as SSL certificates, making it more complex to set up and maintain compared to SFTP. HTTPS is primarily used for secure web communications, not file transfers. AS2 is a protocol specifically designed for secure and reliable data interchange over the Internet, but it may not be as commonly implemented as SFTP for general file transfers within an organization.

Updating DNS records with the correct information is crucial for resolving DNS-related issues that make a website unreachable. This involves accessing the domain registrar or DNS provider's control panel and ensuring that the DNS records (such as A records, CNAME records) are correctly configured to point to the website's hosting server. Checking the DNS configuration on the server helps identify any misconfigurations or discrepancies. Flushing the DNS cache on the client can resolve cached DNS issues but doesn't address incorrect DNS records directly. Testing connectivity using nslookup is a diagnostic step to verify DNS resolution, but it alone does not fix the incorrect records.

NoSQL databases come in various types, each designed for specific data handling needs. Document-oriented databases like MongoDB store data in flexible, JSON-like documents, while key-value stores like Redis use simple key-value pairs. Columnar databases such as Cassandra organize data in columns rather than rows. Graph databases like Neo4j focus on relationships between data entities. Understanding these differences helps in choosing the right database for specific use cases.

Option 2: The default branch name in Git has evolved; historically, it was often 'master,' but newer conventions use 'main.' This is the branch where development typically begins and where stable versions are merged.

Query execution plans show how a database will execute a query, helping to identify inefficient operations and suggesting improvements such as index usage. This insight is crucial for optimizing database queries and improving overall performance.

Database normalization aims to eliminate Functional Redundancy, where the same piece of data is stored in multiple places, leading to inconsistencies and potential data integrity issues.

useState is a React hook that allows functional components to manage state locally. It simplifies state management within a component without the need for class-based components or external libraries like Redux. The other options are also valid for state management, but useState is specifically designed for component-level state management and is a fundamental part of React's modern approach to state handling.

When one thread waits for another to complete its execution, it's termed synchronization. This can involve mechanisms like joining threads or using synchronization primitives like mutexes or semaphores. Suspension refers to temporarily halting a thread's execution, threading is a general term for working with threads, and blocking describes a state where a thread is waiting for an event or resource to become available.

Dynamic programming involves breaking down a complex problem into smaller subproblems, solving each subproblem only once, and storing the solutions to avoid redundant computations. In scheduling, this can be applied by defining the optimal schedule for smaller time intervals and then combining them to obtain the overall optimal schedule. It optimizes the schedule by considering dependencies, resource availability, and time constraints effectively.