Basic Blockchain learning week 2

@Tricdot Education

This test paper start with the exploration of the blockchain and its relation to distributed computing. In particular, we will learn the basics on blockchain abstraction and the importance of consensus between machines in order to mitigate the risks of having an attacker spend the same asset twice - an undesirable situation called 'double-spending'. This question paper inspired from the blockchain course on coursera. Week2/5

This test paper start with the exploration of the blockchain and its relation to distributed computing. In particular, we will learn the basics on blockchain abstraction and the importance of consensus between machines in order to mitigate the risks of having an attacker spend the same asset twice - an undesirable situation called 'double-spending'. This question paper inspired from the blockchain course on coursera. Week2/5

Questions

1. What type of failure is most serious?

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2. Regarding crash failure, which of the following statements is correct?

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3. Regarding arbitrary (a.k.a. Byzantine) failure, which of the following statements is NOT correct?

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4. “Any decided value is a proposed value”. Which consensus property is best described by this statement?

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5. Which impossibility study shows that there is no solution to the consensus problem among n nodes if the number of Byzantine nodes is greater than or equal to a third of all nodes that are trying to solve consensus?

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6. A malicious Byzantine miner mines until it has a branch longer than the ones created by correct miners in the system. Eventually, as the particular system selects the longest branch, the Byzantine miner will have the ability to impose its blocks and the set of transactions it has chosen. The branch that contains blocks created by the correct miners will therefore be discarded. Which of the following attacks best describes the scenario above?

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7. In order to resolve a fork and maintain a single chain, which nodes in the network apply the strategy to choose the particular block that is at each index of the chain.

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8. Which of the following attacks occurs when a malicious Byzantine node creates fake, faulty nodes to the point where the number of faulty nodes exceed a third of the entire set of nodes?

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9. Which of the following problems related to selecting the longest branch does the GHOST protocol seek to address?

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10. Ethereum (as well as the upcoming Ethereum 2.0) consensus is inspired by the GHOST protocol. However, GHOST is different from the existing Ethereum algorithm. What does GHOST take into account that Ethereum does not?

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Index of Questions