The default port number for FTP (File Transfer Protocol) in active mode is 21. FTP is a standard network protocol used for transferring files between a client and a server on a computer network. In active mode, the FTP server listens on port 21 for incoming connections from clients. Once a connection is established, data transfers (such as uploading or downloading files) occur over a separate port, typically port 20 for active mode. Understanding port numbers is crucial for configuring network services and ensuring proper communication between client and server systems.

Using strong consistency models like linearizability or serializability ensures data integrity in a distributed system by guaranteeing that all nodes see the same data at the same time. Implementing eventual consistency with techniques like vector clocks or CRDTs may lead to eventual convergence but does not guarantee immediate consistency. Distributed transactions with two-phase commit protocols can lead to performance issues and increased complexity. Designing a data versioning system with rollback capabilities helps in data recovery but does not directly address data integrity in real-time.

Option 3: Utilizing a Shortest Job Next (SJN) scheduling algorithm can help optimize the scheduling algorithm to reduce context-switching overhead. SJN prioritizes shorter jobs, leading to fewer context switches as shorter jobs are completed more quickly. This approach maintains fairness among processes by executing shorter jobs first while reducing the overall context-switching overhead, improving system efficiency.

Server-side scripting in web development is primarily used for processing data, managing databases, and performing server-side operations, not just displaying content on the client side.

An inode in a Unix-like file system serves the crucial function of storing metadata about files and directories. This metadata includes information such as file ownership, permissions, timestamps (creation, modification, access), file size, and the physical location of data blocks on the storage device. Inodes also store pointers to data blocks, enabling efficient file access and retrieval. Additionally, they play a role in file system consistency and recovery processes.

Implementing data storage mechanisms

Creating separate indexes for name, category, and price allows the database to efficiently retrieve data based on these attributes. Composite indexes combine multiple columns into a single index, which can be beneficial for queries that involve multiple attributes. Full-text search indexes are suitable for searching through large text fields like product descriptions. Implementing indexing based on query frequency involves prioritizing indexes for attributes that are frequently used in search queries, thus optimizing search performance.

Query Optimization is the process of modifying SQL queries to enhance performance, such as reducing execution time or utilizing indexes effectively. Thus, option 1, "Optimization," is the appropriate answer.

Node.js is a common technology used for server-side scripting in JavaScript due to its event-driven architecture and ability to handle I/O operations efficiently.

Implementing a stack using two queues involves leveraging the FIFO (First-In-First-Out) property of queues. By carefully enqueueing and dequeuing elements between two queues, we can simulate the behavior of a stack, where the last-in element is the first to be dequeued.