Questions and Answers
What is Bitcoin?
What does a Bitcoin transaction involve?
Signing a statement that transfers ownership from one Bitcoin address to another.
What is Blockchain?
A sequence of transactions that all nodes must agree on.
What is Bitcoin mining?
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What is the role of blocks in the blockchain?
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What occurs during the Bitcoin consensus process?
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Anyone can mine new blocks for the blockchain.
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What is proof-of-work?
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What is a hard fork?
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What is the Dark Web?
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What is symmetric encryption?
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What is asymmetric encryption?
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What does TLS/SSL provide?
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What does HTTPS example: key exchange involve?
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What is packet switching?
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What does the OS do?
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Which of these are components of OS abstractions? (Select all that apply)
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Which of these are components of hardware? (Select all that apply)
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What is the process abstraction?
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What are the components of a process?
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What do threads share?
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What is a thread?
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When are threads useful?
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What happens in web servers with threads?
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When should you use processes instead of threads?
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What are atomic operations?
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What is the purpose of locks in threading?
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What is a network socket?
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What are cloud services primarily concerned with?
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What is AWS's Elastic Compute Cloud (EC2)?
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What is the concept of virtualization?
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What is Boolean retrieval?
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What does TF x IDF represent?
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What is MapReduce?
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What are the main functions of a central bank?
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What is round robin DNS?
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What does load balancing do?
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What is Jaccard Similarity Coefficient?
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Study Notes
Operating System Fundamentals
- OS creates abstractions to simplify hardware usage and manages shared resources.
- Key abstractions of the OS include Process, File System, Virtual Memory, and Sockets.
Hardware Components
- Essential hardware components are CPU, Disk, RAM, and Network.
Process Abstraction
- Represents a program in execution, containing address space, threads, and resources like file handles.
- Each process is identified by a unique Process ID (PID) and maintains execution state.
Threads and Their Functionality
- Threads are active entities of execution sharing code and resources such as heap memory and global variables.
- Each thread has a private execution stack and registers to maintain its state.
- Multithreading is useful for achieving parallelism during resource-intensive tasks, e.g., network servers.
Communication via Sockets
- Sockets enable network communication, with TCP providing reliable connections while UDP sends unordered packets.
- A typical socket connection involves BINDing, LISTENing, and accepting requests.
Cloud Services and Virtualization
- Key cloud service models include IaaS, SaaS, and PaaS.
- AWS services like EC2 and S3 provide virtual computing and storage solutions through virtualization techniques.
Search Engine Models
- Boolean retrieval provides simplistic true/false output but is ineffective.
- The term-document incidence table maps terms to documents for efficient querying.
Document Representation and Indexing
- Documents can be viewed as vectors, measuring term frequency for similarity assessment.
- TF-IDF (Term Frequency-Inverse Document Frequency) scores help weigh document relevance based on common and rare terms.
Evaluation Metrics
- Precision measures relevant documents retrieved, while Recall indicates relevant documents identified out of total available.
- Kendall's tau and Mean Reciprocal Rank provide rank correlation and position of first correct answers, respectively.
PageRank Algorithm
- PageRank operates on a directed graph of web pages. Pages receive scores based on links from important pages.
- Sink nodes may gather rank without outgoing links, requiring methods to prevent rank drain.
Crawling and Indexing Strategies
- Web crawlers index all static pages, while dynamic pages depend on server-side links.
- Inverted indexes allow quick access by mapping terms to associated documents.
Data Management Techniques
- Deduplication ensures document uniqueness through methods like shingling and the Jaccard similarity coefficient.
- MapReduce framework enables efficient large-scale data processing by breaking tasks into mappable and reducible components.
Bitcoin and Digital Currency
- Bitcoin operates as a decentralized digital currency based on blockchain technology and requires cryptographic security for transactions.
- Transactions involve public and private keys, maintaining ownership without a central authority.
Blockchain Characteristics
- A blockchain is a sequential, tamper-proof transaction record built from blocks containing metadata and transaction data, guaranteeing the integrity of digital currencies like Bitcoin.### Bitcoin Consensus
- Transactions are disseminated to all network nodes, where a random node signs a block containing new transactions and the hash of the previous block.
- If transactions are valid, other nodes accept the new block; invalid transactions are ignored.
- The process is repeated for subsequent blocks, with the longest chain deemed canonical.
- A valid canonical chain requires an "honest majority" to prevent manipulation.
Mining the Blockchain
- Anyone can mine blocks for the blockchain, but mining is necessary as a block's validity relies on its hash being below a target value.
- The hashing process requires significant time and computational effort.
Proof-of-Work
- Proof-of-work puzzles are designed to be difficult to compute but easy to validate.
- A solution to this puzzle serves as proof of spent computational effort.
- The target difficulty can be adjusted to calibrate mining speed, aiming for an average of 10 minutes per block.
Blockchain Forks
- Concurrent discovery of a new block by two miners can lead to a fork.
- The fork that grows quicker, due to more computational power, is considered valid.
- A fork can result in a new cryptocurrency, differentiating transaction histories and ownership versions.
Bitcoin Miners' Motivation
- Miners, as block creators, can reward themselves with bitcoins from transaction inclusions.
- This process is fundamental for both earning bitcoins and increasing the total supply of the cryptocurrency.
Bitcoin Reward Function
- The reward for mining bitcoins halves approximately every four years to control inflation.
Bitcoin Creation Difficulty Adjustment
- The complexity of creating a nonce for blocks increases over time, making mining progressively more challenging.
Hard Fork
- A hard fork creates two distinct cryptocurrencies from one, sharing a partial transaction history.
- Holders of the original asset will possess both new assets, often resulting in higher combined market values.
- All nodes must upgrade their software for the hard fork to take effect.
The Dark Web
- The dark web is a concealed part of the internet, accessible only through specific anonymous networks.
- It is enveloped by the deeper segment of the internet known as the deep web.
Packet Switching
- The internet operates on a best-effort, packet-switched model with packets being the fundamental unit of data transmission.
- Packets may experience delays or failures in transit, with IP routers central to internet functioning.
Internet Protocol (IP)
- IP operates in a connectionless manner, utilizing a "store and forward" mechanism.
- Different packets can take diverse paths to reach the same destination.
- Accurate destination information is crucial; otherwise, packets cannot be delivered.
Desirable Properties of Communication
- Essential properties include confidentiality, sender authenticity, message integrity, freshness, and anonymity.
Symmetric Encryption
- Utilizes the same key for both encoding and decoding messages, ensuring fast computation.
- Provides confidentiality by preventing unauthorized understanding of the message.
Asymmetric Encryption
- Involves a pair of keys: public and private.
- One key encrypts the message while the other decrypts it, with the keys being mathematically independent.
Public Key Infrastructure
- Certificate authorities (CAs) are responsible for verifying identities and public keys.
- Public keys for major CAs are integrated into web browsers.
TLS/SSL - Transport Layer Security/Secure Sockets Layer
- Indicated by "https://", this protocol encrypts all content in the TCP payload to ensure secure communication.
HTTPS Example: Certificate Exchange
- The server verifies its identity to the client by sending an SSL certificate and its public key.
- The client checks the certificate against a list of trusted CAs to confirm the server's legitimacy.
HTTPS Example: Key Exchange
- The client generates a random key for future symmetric encryption and encrypts it using the server's public key.
- Later, traffic is secured using symmetric encryption with the agreed shared key.
Packet Inspection
- Each network packet contains source and destination IP addresses, with source addresses potentially being spoofed.
- The packet's source and destination information is observable by any entity monitoring the network.
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Description
This quiz covers fundamental concepts related to Bitcoin and blockchain technology. Explore key topics such as Bitcoin transactions, mining processes, and the role of consensus in the blockchain system. Perfect for beginners looking to deepen their understanding of cryptocurrencies.