Explanation

• A DoS attack floods a system or server with excessive traffic or requests.
• It makes the service slow or unavailable to legitimate users.
• DDoS (Distributed Denial-of-Service): Uses multiple devices to launch the attack.

Explanation

• SQL injection exploits unsanitized or improperly handled user input in database queries.
• Attackers manipulate SQL statements to access or modify data without authorization.
• Prevention: Use parameterized queries (prepared statements).

Explanation

• COUNT(*) counts all rows in a table.
• If the table is empty, it returns 0.
• It counts rows regardless of NULL values in individual columns.

Explanation

• DISTINCT returns only unique rows or values.
• It removes duplicate results from a query.
• It is used with the SELECT statement.

Explanation

• A subquery is a query written inside another SQL query.
• It is enclosed in parentheses ().
• It can be used with SELECT, INSERT, UPDATE, and DELETE statements.

Explanation

• View: A virtual table based on an SQL query.
• Materialized View: A stored copy of query results.
• Main Difference: A view stores the query; a materialized view stores the query results.

Explanation

• Merge Sort uses the divide-and-conquer algorithmic technique.
• Merge Sort divides the array into smaller subarrays.
• It sorts each subarray recursively.
• Finally, it merges them into one sorted array.
• Time Complexity: O n log n

Explanation

• Transport Layer provides error recovery and retransmission.
• Layer: The 4th layer of the OSI model.
• Example: TCP (Transmission Control Protocol).

Additional information:

The OSI (Open Systems Interconnection) model has 7 layers:

1. Application: Network services (HTTP, FTP)

2. Presentation: Encryption, formatting, compression

3. Session: Manages communication sessions

4. Transport: End-to-end delivery, flow control (TCP)

5. Network: Routing and IP addressing

6. Data Link: MAC addressing and error detection

7. Physical: Transmits raw bits through cables or wireless signals

Explanation

• MS Excel: Application software used for spreadsheets, calculations, and data analysis.
• Windows, Linux, DOS: Operating systems (system software).

Explanation

• SSD: Uses flash memory; faster and has no moving parts.
• HDD: Uses spinning magnetic disks; slower and has moving parts.
• SSD is generally more durable and quieter than an HDD.
• SSD: Solid-State Drive
• HDD: Hard Disk Drive