Virtual Labs

Understanding Byzantine Failures in Distributed Systems

In a distributed system, what is a 'node'?

a: A type of network cable. Explanation

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b: An independent computer within the system. Explanation

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c: A user of the system. Explanation

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d: A software bug. Explanation

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Which of these is NOT a primary category of failure in distributed systems?

a: Crash Failure Explanation

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b: Cosmetic Failure Explanation

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c: Omission Failure Explanation

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d: Byzantine Failure Explanation

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What does it mean for a Byzantine node to behave 'arbitrarily'?

a: It always crashes. Explanation

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b: It can do anything, including sending wrong or conflicting information. Explanation

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c: It only sends messages late. Explanation

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d: It stops sending messages. Explanation

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In the PBFT algorithm, what is the purpose of the 'prepare' phase?

a: The client prepares a request to send. Explanation

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b: The primary node prepares to send the request to backups. Explanation

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c: Backup nodes broadcast their agreement on the request's sequence number. Explanation

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d: The client prepares to receive the final reply. Explanation

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If a BFT system has 7 nodes in total, what is the maximum number of Byzantine nodes it can tolerate?

a: 1 Explanation

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b: 2 Explanation

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c: 3 Explanation

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d: 4 Explanation

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Why is the condition n > 3t necessary for Byzantine fault tolerance?

a: To ensure messages are delivered quickly. Explanation

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b: To ensure that after the 't' traitors send their messages, the remaining loyal nodes have a majority. Explanation

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c: It's an arbitrary number chosen by researchers. Explanation

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d: To make the system more expensive to build. Explanation

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In the context of PBFT, what does the 'commit' phase signify?

a: A node has received the client's request. Explanation

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b: A node has prepared the message. Explanation

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c: A node has received enough 'prepare' messages to be certain that a sufficient number of other nodes agree on the request. Explanation

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d: The client has committed the result to its local storage. Explanation

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How does PBFT prevent a faulty primary node from causing system failure?

a: The primary node can never be faulty. Explanation

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b: Backups can initiate a 'view change' protocol to elect a new primary if the current one is suspected to be faulty. Explanation

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c: The client can choose a different primary. Explanation

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d: The system shuts down if the primary is faulty. Explanation

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Which of the following real-world systems would have the MOST critical need for Byzantine Fault Tolerance?

a: A personal blog website. Explanation

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b: A video streaming service. Explanation

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c: An international funds transfer system. Explanation

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d: A collaborative document editor. Explanation

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