Consensus and Scalability Innovations BDC Practice Questions (Page 7)

Questions 31–35

1. 31foundation · easy

   Which of the following is a scalability limitation of Proof of Work?

   • AIt requires a large amount of computational energy and time to add blocks
   • BIt requires a minimum number of nodes to be online
   • CIt does not provide any security against double-spending
   • DIt can only be used in permissioned blockchains
   Reveal Solution Discussion Select an answer first
2. 32application · medium

   A blockchain-based voting platform wants to use Delegated Proof of Stake (DPoS) to increase throughput. They are concerned about the possibility of a few delegates colluding to manipulate the network. What is a common mitigation?

   • AUse a DAG-based structure instead of DPoS to avoid delegate collusion.
   • BUse a fixed set of delegates that cannot be changed.
   • CImplement a mechanism for token holders to vote out delegates who act maliciously.
   • DIncrease the block reward to incentivize honest behavior.
   Reveal Solution Discussion Select an answer first
4. 33expert · hard

   A consortium of banks is building a permissioned blockchain for interbank settlements. They need high throughput and low latency, but they also require strong finality and the ability to handle cross-shard transactions without compromising security. They are considering sharding the network. Which design decision is most critical to ensure that cross-shard transactions do not become a bottleneck?

   • AImplement sharding only at the network layer, not at the state or transaction level.
   • BUse a sharding protocol that supports atomic cross-shard transactions via a coordinator or two-phase commit.
   • CAssign each bank to its own shard and allow each shard to operate independently without cross-shard communication.
   • DUse a single shard for all high-value transactions and shard only low-value ones.
   Reveal Solution Discussion Select an answer first
5. 34foundation · easy

   In sharding, what is a 'shard'?

   • AA cryptographic hash of a block
   • BA type of consensus algorithm
   • CA special node that validates all transactions
   • DA portion of the network that processes a subset of transactions
   Reveal Solution Discussion Select an answer first
6. 35application · medium

   A payment processor wants to reduce the load on a public blockchain by batching many off-chain transactions into a single on-chain transaction. They need to ensure that the data is available and can be verified. Which Layer 2 solution is most appropriate?

   • AOptimistic rollup, which posts transaction data to the main chain and assumes validity unless challenged.
   • BState channel, which allows two parties to transact off-chain and only settle the final state.
   • CPlasma, which uses child chains and fraud proofs, but does not post all transaction data on-chain.
   • DSidechain, which runs its own consensus and periodically anchors to the main chain.
   Reveal Solution Discussion Select an answer first