Alternative and Hybrid Consensus Mechanisms BDC Practice Questions (Page 4)

Questions 16–20

1. 16application · medium

   A financial institution wants to build a settlement blockchain that must be permissioned (only vetted banks can participate) but also needs to prove to regulators that the ledger hasn't been tampered with. They have a budget for 50 validator nodes. Which hybrid consensus approach best meets these needs?

   • APBFT among the 50 bank validators, with periodic Merkle-root commitments published to a public blockchain
   • BProof-of-Authority with one bank as the sole block producer
   • CPure Proof-of-Work with the 50 banks mining blocks
   • DPure Proof-of-Stake where only the 50 banks can stake
   Reveal Solution Discussion Select an answer first
2. 17application · medium

   A developer is comparing hybrid consensus designs for a new blockchain. They want a system where block producers are elected by stake but their power is checked by a separate group of randomly selected validators who must approve each block. Which hybrid model best matches this description?

   • AA pure proof-of-authority network with a fixed set of known validators
   • BA delegated proof-of-stake system with a rotating validator set
   • CA hybrid of DPoS and a randomly selected jury that ratifies blocks
   • DDecred's PoW/PoS hybrid
   Reveal Solution Discussion Select an answer first
4. 18application · medium

   A developer is evaluating Decred as a model for a new project. They want to understand how Decred's hybrid consensus achieves both security and community governance. Which statement accurately describes Decred's design?

   • APoW miners produce blocks, and PoS stakeholders vote on each block to approve or reject it
   • BPoW miners and PoS stakeholders each maintain separate blockchains
   • CBoth PoW miners and PoS stakeholders produce blocks in a round-robin fashion
   • DPoS stakeholders produce blocks, and PoW miners vote on each block
   Reveal Solution Discussion Select an answer first
5. 19expert · hard

   A developer is comparing Decred's hybrid consensus with a simple PoW+PoS checkpointing system (like Casper FFG). They need to explain to a client the key difference in how each handles block production. Which statement is accurate?

   • AIn Casper FFG, PoS validators produce blocks and PoW miners only secure the chain history
   • BIn Decred, PoS ticket holders must approve each block for it to be valid, while in Casper FFG, PoS validators only finalize checkpoints and PoW miners produce all blocks independently
   • CIn Decred, PoW miners produce blocks and PoS validators only vote on governance proposals, not on block validity
   • DIn both systems, PoS validators must approve every block before it is added to the chain
   Reveal Solution Discussion Select an answer first
6. 20application · medium

   A fintech startup is building a digital currency for a consortium of banks. They need a system that provides fast finality for interbank settlements but also want to avoid the energy overhead of proof-of-work. They are evaluating Decred's hybrid model as a reference. Which aspect of Decred's design would be most relevant to their finality and energy goals?

   • AReplacing proof-of-work entirely with a delegated proof-of-stake committee
   • BRunning two independent blockchains and cross-chaining transactions between them
   • CUsing a single leader elected by coin age to produce all blocks
   • DUsing proof-of-stake voters to ratify blocks produced by proof-of-work miners
   Reveal Solution Discussion Select an answer first