Block Chain & Crypto-Currencies (CY-702 (B)) - Important Questions

Explain the architecture of a blockchain. Describe the role and interaction of its main components such as nodes, peer-to-peer network, ledger, blocks, transactions, headers, and Merkle trees. Also explain how immutability and decentralization are achieved in this architecture.

Describe the permissioned model of blockchain. Explain its key characteristics, typical access and governance controls, advantages and disadvantages, and give practical use-case examples where permissioned blockchains are preferred.

Explain consensus algorithms used in blockchain. Compare Proof-of-Work (PoW) and Proof-of-Stake (PoS) in terms of working principle, security properties, energy/resource usage, attack vectors and typical suitability for different blockchain types.

Explain how Merkle trees are constructed and how they are used to verify transaction inclusion in a block. Include a brief description of Merkle root and its role in block headers.

Discuss the working of Bitcoin. Describe the block structure, transaction format, addresses, and explain how mining secures the Bitcoin network including an outline of how double-spending is prevented.

Compare public, private and permissioned blockchains. For each model, describe core properties (access control, trust assumptions, consensus type), and give two example applications or industries best suited to each model.

Describe the architecture of Ethereum and explain the role of the Ethereum Virtual Machine (EVM). Discuss how smart contracts are executed and how state and gas are used within the EVM.

Explain how transactions are validated and blocks are agreed upon in a permissioned blockchain. Describe common consensus mechanisms used in permissioned systems (for example PBFT, Raft) and highlight how they differ from public blockchain consensus approaches.