Consensus and Scalability Innovations BDC Practice Questions (Page 1)

Questions 1–5

1. 1foundation · easy

   In Proof of Stake (PoS), what determines a validator's chance of being selected to propose the next block?

   • AThe validator's geographic location
   • BThe validator's reputation score from previous blocks
   • CThe amount of computational power the validator contributes
   • DThe number of coins the validator has staked, often combined with randomization
   Reveal Solution Discussion Select an answer first
2. 2expert · hard

   A government agency is deploying a permissioned blockchain for land registry records. They require high throughput and finality, but they also need to tolerate up to one-third of the nodes being malicious without halting. The network has 10 known nodes. Which consensus mechanism should they select?

   • ASharding with PoS, because it partitions the network into shards to increase throughput.
   • BPBFT, because it provides immediate finality and can tolerate up to one-third faulty nodes.
   • CPoW, because it is the most secure and can tolerate any number of malicious nodes.
   • DDPoS, because it elects a small set of delegates that can be easily replaced if they misbehave.
   Reveal Solution Discussion Select an answer first
4. 3expert · hard

   A blockchain startup is choosing between PoW and PoS for a new public network. They value security against 51% attacks and want to minimize energy consumption. They also want to avoid the risk of a 'nothing at stake' problem. Which consensus mechanism should they choose, and why?

   • APoS, because it reduces energy consumption and can use slashing to penalize validators who sign conflicting blocks, mitigating the nothing-at-stake problem.
   • BPoW, because it is the only consensus that can prevent 51% attacks.
   • CPoS, because it completely eliminates the risk of 51% attacks.
   • DPoW, because it has no energy consumption and is therefore more sustainable.
   Reveal Solution Discussion Select an answer first
5. 4application · medium

   A gaming company runs a blockchain-based game on a public Ethereum-like network. Players make thousands of micro-transactions per second, but the base layer cannot handle the load. They want to keep the security of the main chain while moving most transactions off-chain. Which solution should they implement?

   • AUse a state channel that requires both players to stay online to sign every micro-transaction.
   • BDeploy an optimistic rollup that batches many transactions off-chain and submits a compressed proof to the main chain.
   • CMove all game logic to a sidechain with its own consensus, and periodically snapshot the state to the main chain.
   • DIncrease the block gas limit on the main chain to allow more transactions per block.
   Reveal Solution Discussion Select an answer first
6. 5foundation · easy

   Which of the following is an emerging trend in consensus algorithms?

   • AProof of History
   • BDelegated Proof of Work
   • CProof of Work
   • DProof of Authority
   Reveal Solution Discussion Select an answer first