How to answer this Technical interview question about Consensus Algorithm for Senior-Level Blockchain Developer?

How would you implement a consensus algorithm for a private blockchain?

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Blockchain Developer

Technical

Asked at

IBM Blockchain

Difficulty :

Hard

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Explanation

This question evaluates your ability to design and implement consensus algorithms tailored to a private blockchain environment. Recruiters assess your understanding of consensus mechanisms like PBFT, Raft, or Proof of Authority (PoA), and their implementation challenges. Common pitfalls include not addressing scalability or failing to justify the chosen algorithm. A strong answer includes selecting the right algorithm, explaining its suitability, and addressing implementation details. Preparation involves studying private blockchain frameworks like Hyperledger Fabric.

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Answer Example

I would select a consensus algorithm based on the private blockchain’s requirements, such as low latency and high throughput. For example, I would choose PBFT (Practical Byzantine Fault Tolerance) for its ability to handle malicious nodes effectively. I would implement the algorithm by configuring nodes to participate in block validation and ensuring fault tolerance through node replication and secure communication channels. For instance, I implemented PBFT in a supply chain blockchain, achieving transaction finality in under two seconds.

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