Proof of Stake (PoS) and Derivative Protocols BDC Practice Questions (Page 1)

Questions 1–5

1. 1foundation · easy

   What is a long-range attack in Proof of Stake?

   • AAn attacker sends a large number of transactions to slow down the network
   • BAn attacker gains control of more than 51% of the network's hash power
   • CAn attacker exploits a smart contract vulnerability to drain funds
   • DAn attacker uses old private keys to forge an alternative history from a point far in the past
   Reveal Solution Discussion Select an answer first
2. 2expert · hard

   A Delegated Proof of Stake network has 21 delegates. A group of large token holders colludes to control 11 delegates and attempts to censor transactions. What is the most effective countermeasure available to the community?

   • AImplement a hard fork to remove the colluding delegates
   • BIncrease the block size to make censorship harder
   • CVote out the colluding delegates and replace them with honest ones
   • DRequire delegates to post a larger bond
   Reveal Solution Discussion Select an answer first
4. 3expert · hard

   A PoS network is considering a change to reduce the minimum stake required to become a validator from 10,000 tokens to 1,000 tokens, aiming to increase decentralization. However, the network is also concerned about the 'nothing-at-stake' problem. What is the most important additional measure to implement alongside the lower minimum stake?

   • AIncrease the block reward to compensate validators for the higher risk.
   • BShorten the block time to make the chain more responsive.
   • CAllow validators to withdraw their stake at any time to increase flexibility.
   • DImplement a robust slashing mechanism that penalizes validators who vote on conflicting forks, even if the penalty is small.
   Reveal Solution Discussion Select an answer first
5. 4expert · hard

   A Proof of Stake network is experiencing a 'stake grinding' attack where validators manipulate the random seed to increase their chances of being selected. Which mitigation is most effective?

   • AUse a verifiable random function (VRF) with a secret per-validator key to generate randomness
   • BUse the previous block hash as the random seed
   • CShorten the epoch length to reduce the time for manipulation
   • DIncrease the number of validators to make manipulation harder
   Reveal Solution Discussion Select an answer first
6. 5foundation · easy

   What is a key benefit of Leased Proof of Stake (LPoS) for small token holders?

   • AThey are exempt from any risk of losing their tokens
   • BThey can earn staking rewards without running a full node or meeting a high minimum stake requirement
   • CThey gain direct control over block production decisions
   • DThey receive a fixed guaranteed return regardless of network conditions
   Reveal Solution Discussion Select an answer first