Finality in Blockchain Consensus BFC Practice Questions (Page 8)

Questions 36–40

1. 36application · medium

   A PoS blockchain uses checkpoints to finalize historical blocks. A validator is considering whether to sign a block that conflicts with a checkpointed block. What is the most likely consequence?

   • AThe network will ignore the checkpoint
   • BThe checkpoint will be moved
   • CThe validator will be slashed
   • DThe validator will lose only future rewards
   Reveal Solution Discussion Select an answer first
2. 37expert · hard

   A PoS blockchain is experiencing a liveness issue: validators cannot agree on a new checkpoint because of a network partition. The protocol uses a finality gadget that requires 2/3 of validators to vote. What is the most likely consequence?

   • AThe chain will stop finalizing new checkpoints until the partition heals
   • BThe checkpoint will be finalized by a single validator
   • CValidators will be slashed for not voting
   • DThe chain will automatically revert to PoW
   Reveal Solution Discussion Select an answer first
4. 38application · medium

   A payment processor using a PoW blockchain wants to reduce the risk of accepting a transaction that is later reversed. Which action would most effectively reduce this risk?

   • AUse a smaller block size
   • BIncrease the number of confirmations required
   • CDecrease the transaction fee
   • DRequire the transaction to be included in the mempool
   Reveal Solution Discussion Select an answer first
5. 39expert · hard

   A blockchain team is designing a system that must provide immediate finality but also remain live even if some validators are slow due to network partitions. They are considering PBFT. Which aspect of PBFT is most likely to cause a liveness issue under network partitions?

   • AThe probabilistic nature of finality
   • BThe need for a supermajority (2/3) of validators to agree
   • CThe absence of a leader
   • DThe use of cryptographic signatures
   Reveal Solution Discussion Select an answer first
6. 40foundation · easy

   What is a trade-off of PBFT-based consensus compared to Proof of Work?

   • AIt requires more confirmations to achieve finality
   • BIt provides weaker finality guarantees
   • CIt is more energy-intensive
   • DIt requires more communication overhead and is less scalable to large networks
   Reveal Solution Discussion Select an answer first