Alternative and Hybrid Consensus Mechanisms BDC Practice Questions (Page 7)

Questions 31–35

1. 31application · medium

   A startup is building a blockchain for a voting system. They need high integrity and resistance to manipulation, but they also want to minimize energy consumption. They are considering a hybrid that uses proof-of-stake for block production and a randomly selected committee for finality. What is the main security advantage of the random committee?

   • AIt guarantees that the committee will always act honestly
   • BIt eliminates the need for any token staking
   • CIt ensures that all validators are equally wealthy
   • DIt makes it harder for an attacker to predict who will finalize a block, reducing the chance of targeted bribery
   Reveal Solution Discussion Select an answer first
2. 32expert · hard

   A blockchain startup is designing a hybrid consensus for a decentralized social media platform. They want to prevent a small group of wealthy users from controlling the network, but they also want to avoid the energy costs of proof-of-work. They are considering a hybrid that uses proof-of-stake for block production and a randomly selected committee for governance. Which trade-off is most important to evaluate?

   • AThe random committee may be vulnerable to statistical manipulation if the randomness source is not secure
   • BThe hybrid will consume more energy than a pure PoW system
   • CThe PoS block producers will always act in the best interest of the network
   • DThe random committee eliminates the need for any token distribution
   Reveal Solution Discussion Select an answer first
4. 33foundation · easy

   Why would a blockchain project choose a hybrid consensus mechanism instead of a single consensus algorithm?

   • ATo achieve a more favorable balance of properties that a single algorithm cannot provide on its own
   • BTo ensure that only one type of participant can validate transactions
   • CTo guarantee that the network is completely immune to all types of attacks
   • DTo make the consensus process simpler and easier to implement
   Reveal Solution Discussion Select an answer first
5. 34application · medium

   A supply-chain consortium wants a blockchain that can process thousands of transactions per second but also needs to prevent a small group of validators from unilaterally rewriting history. They are considering a hybrid consensus that combines a high-throughput BFT protocol with a periodic proof-of-work checkpointing mechanism. What is the primary security benefit of adding the PoW checkpointing layer?

   • AIt eliminates the need for any trusted validators in the BFT layer
   • BIt provides an immutable anchor that makes historical reorganization increasingly difficult over time
   • CIt allows the network to run without any form of sybil resistance
   • DIt reduces the latency of each transaction to near zero
   Reveal Solution Discussion Select an answer first
6. 35expert · hard

   A developer must choose a consensus mechanism for a blockchain that will be used for a national digital identity system. The system must be permissioned (only government-approved entities can validate), must provide finality in under 1 second, and must remain available even if 2 of 7 validator nodes are compromised. Which consensus mechanism should they select?

   • APBFT with 7 validators, which tolerates up to 2 Byzantine faults and provides deterministic finality in under 1 second
   • BDelegated Proof-of-Stake with 7 elected delegates
   • CProof-of-Authority with 7 validators where any 1 validator can produce a block
   • DRaft with 7 validators, which tolerates up to 3 node failures and provides fast finality
   Reveal Solution Discussion Select an answer first