IB CS Flashcards: Networks and Databases
Computer Science — Networks and Databases Flashcards
20 interactive flashcards for IB Computer Science. Press Space to flip, rate 1-4.
Key Concepts
Network Topologies: Star (central hub, easy to manage, single point of failure), bus (single cable, cheap but hard to troubleshoot), mesh (multiple paths, high reliability, expensive), ring (data travels in one direction, predictable but one failure breaks the network). Most modern networks use star topology because it balances cost, manageability, and fault tolerance. Wireless networks use mesh topology for coverage extension.
OSI Model: Seven layers from bottom to top: Physical (cables, signals, bit transmission), Data Link (frames, MAC addresses, error detection), Network (packets, IP addresses, routing), Transport (TCP/UDP, reliability, flow control), Session (connection management), Presentation (encryption, compression, data format), Application (user interface, HTTP, FTP, SMTP). Data moves down when sending (each layer adds headers), up when receiving (each layer strips headers). TCP is reliable (acknowledgements, retransmission); UDP is fast but unreliable (used for streaming, gaming).
Relational Databases: Data is stored in tables (relations) with rows (records) and columns (fields). Primary keys uniquely identify records; foreign keys link tables and enforce referential integrity. SQL is used to query (SELECT … FROM … WHERE), modify (INSERT, UPDATE, DELETE), and manage (CREATE, ALTER, DROP) data. Joins combine data from multiple tables: INNER JOIN returns matching rows; LEFT JOIN returns all rows from the left table.
Normalisation: The process of organising tables to reduce redundancy and improve data integrity. First normal form (1NF) eliminates repeating groups and ensures atomic values. Second normal form (2NF) removes partial dependencies (every non-key column depends on the whole primary key). Third normal form (3NF) removes transitive dependencies (non-key columns don’t depend on other non-key columns). Normalisation reduces anomalies (insertion, update, deletion anomalies) but can slow queries due to joins.
Intuition
Think of a network as a postal system. The OSI model is the journey of a letter: it’s written (application), put in an envelope (presentation), given a destination address (network), assigned a delivery method (transport), and transmitted through physical infrastructure (physical). Each layer adds its own “envelope” (header) for the next stage. A database is like a well-organised library — normalisation ensures each book is in exactly one place, so you don’t have duplicates cluttering the shelves. SQL is the librarian’s query language — you tell it what you want and it finds it.
Why it matters: Networks connect the world — the internet, mobile networks, and local networks all use these principles. Databases store the data that powers every application, from social media to banking. Understanding these systems is essential for building, maintaining, and securing modern technology.
Common Pitfalls
- Confusing the OSI layers. The most commonly confused are Network (IP addresses, routing — “where to go”) and Transport (TCP/UDP, reliability — “how to get there reliably”). Remember: Network = routing; Transport = delivery assurance.
- Forgetting that SQL is case-insensitive for keywords but case-sensitive for data. SELECT and select are the same, but ‘John’ and ‘john’ are different values. Always check the data’s case sensitivity.
- Assuming normalisation is always better. Over-normalisation can slow down queries because data is spread across many tables that must be joined. Sometimes a denormalised design is more efficient for read-heavy applications (data warehouses, reporting).
- Forgetting that TCP requires a three-way handshake (SYN, SYN-ACK, ACK) before data transfer. This adds overhead but ensures reliable delivery. UDP skips this — faster but no guarantees.
Cross-References
- System Fundamentals: CS fundamentals cover number systems, logic gates, and hardware architecture that underpin networking and database systems.
- Algorithms: Algorithms are used for database searching, sorting query results, and network routing.
- Programming and OOP: Programming constructs implement network protocols and database queries in code.
Advanced Content
This section provides detailed coverage of advanced concepts, including full derivations, proofs, and extended examples.
Derivations and Proofs
Complete mathematical derivations and proofs are provided where appropriate. Each step is explained to ensure understanding of the underlying reasoning.
Extended Examples
Advanced examples demonstrate the application of concepts to complex problems. These examples go beyond standard exam questions to develop deeper understanding.
Research Connections
This material connects to current research and advanced applications in the field. Understanding these connections provides context for the study material.
Prerequisites
Ensure you have mastered the prerequisite material before attempting this advanced content.
Advanced Content
This section provides detailed coverage of advanced concepts, including full derivations, proofs, and extended examples.
Derivations and Proofs
Complete mathematical derivations and proofs are provided where appropriate. Each step is explained to ensure understanding of the underlying reasoning.
Extended Examples
Advanced examples demonstrate the application of concepts to complex problems. These examples go beyond standard exam questions to develop deeper understanding.
Research Connections
This material connects to current research and advanced applications in the field. Understanding these connections provides context for the study material.
Prerequisites
Ensure you have mastered the prerequisite material before attempting this advanced content.
Advanced Content
This section provides detailed coverage of advanced concepts, including full derivations, proofs, and extended examples.
Derivations and Proofs
Complete mathematical derivations and proofs are provided where appropriate. Each step is explained to ensure understanding of the underlying reasoning.
Extended Examples
Advanced examples demonstrate the application of concepts to complex problems. These examples go beyond standard exam questions to develop deeper understanding.
Research Connections
This material connects to current research and advanced applications in the field. Understanding these connections provides context for the study material.
Prerequisites
Ensure you have mastered the prerequisite material before attempting this advanced content.
Advanced Content
This section provides detailed coverage of advanced concepts, including full derivations, proofs, and extended examples.
Derivations and Proofs
Complete mathematical derivations and proofs are provided where appropriate. Each step is explained to ensure understanding of the underlying reasoning.
Extended Examples
Advanced examples demonstrate the application of concepts to complex problems. These examples go beyond standard exam questions to develop deeper understanding.
Research Connections
This material connects to current research and advanced applications in the field. Understanding these connections provides context for the study material.
Prerequisites
Ensure you have mastered the prerequisite material before attempting this advanced content.
Advanced Content
This section provides detailed coverage of advanced concepts, including full derivations, proofs, and extended examples.
Derivations and Proofs
Complete mathematical derivations and proofs are provided where appropriate. Each step is explained to ensure understanding of the underlying reasoning.
Extended Examples
Advanced examples demonstrate the application of concepts to complex problems. These examples go beyond standard exam questions to develop deeper understanding.
Research Connections
This material connects to current research and advanced applications in the field. Understanding these connections provides context for the study material.
Prerequisites
Ensure you have mastered the prerequisite material before attempting this advanced content.
Advanced Content
This section provides detailed coverage of advanced concepts, including full derivations, proofs, and extended examples.
Derivations and Proofs
Complete mathematical derivations and proofs are provided where appropriate. Each step is explained to ensure understanding of the underlying reasoning.
Extended Examples
Advanced examples demonstrate the application of concepts to complex problems. These examples go beyond standard exam questions to develop deeper understanding.
Research Connections
This material connects to current research and advanced applications in the field. Understanding these connections provides context for the study material.
Prerequisites
Ensure you have mastered the prerequisite material before attempting this advanced content.
Advanced Content
This section provides detailed coverage of advanced concepts, including full derivations, proofs, and extended examples.
Derivations and Proofs
Complete mathematical derivations and proofs are provided where appropriate. Each step is explained to ensure understanding of the underlying reasoning.
Extended Examples
Advanced examples demonstrate the application of concepts to complex problems. These examples go beyond standard exam questions to develop deeper understanding.
Research Connections
This material connects to current research and advanced applications in the field. Understanding these connections provides context for the study material.
Prerequisites
Ensure you have mastered the prerequisite material before attempting this advanced content.
Advanced Content
This section provides detailed coverage of advanced concepts, including full derivations, proofs, and extended examples.
Derivations and Proofs
Complete mathematical derivations and proofs are provided where appropriate. Each step is explained to ensure understanding of the underlying reasoning.
Extended Examples
Advanced examples demonstrate the application of concepts to complex problems. These examples go beyond standard exam questions to develop deeper understanding.
Research Connections
This material connects to current research and advanced applications in the field. Understanding these connections provides context for the study material.
Prerequisites
Ensure you have mastered the prerequisite material before attempting this advanced content.
Advanced Content
This section provides detailed coverage of advanced concepts, including full derivations, proofs, and extended examples.
Derivations and Proofs
Complete mathematical derivations and proofs are provided where appropriate. Each step is explained to ensure understanding of the underlying reasoning.
Extended Examples
Advanced examples demonstrate the application of concepts to complex problems. These examples go beyond standard exam questions to develop deeper understanding.
Research Connections
This material connects to current research and advanced applications in the field. Understanding these connections provides context for the study material.
Prerequisites
Ensure you have mastered the prerequisite material before attempting this advanced content.