Byzantine Fault Tolerant (BFT) Mechanisms BDC Practice Questions (Page 4)

Questions 16–20

1. 16foundation · medium

   Which of the following is a key difference between Byzantine fault tolerance (BFT) and crash fault tolerance (CFT)?

   • ABFT addresses malicious or arbitrary behavior, while CFT only addresses nodes that stop responding.
   • BBFT is easier to implement than CFT because it requires fewer messages.
   • CCFT assumes faulty nodes may send conflicting messages, while BFT assumes they only stop.
   • DBFT can tolerate more faulty nodes than CFT for the same total number of nodes.
   Reveal Solution Discussion Select an answer first
2. 17application · medium

   A security auditor is reviewing a permissioned blockchain that uses a crash-fault-tolerant consensus algorithm. The auditor warns that the network is vulnerable to a specific type of attack. Which attack is the auditor most likely referring to?

   • AA validator accidentally sending a malformed message
   • BA malicious validator sending conflicting blocks to different nodes
   • CA node losing power and restarting with an old state
   • DA network partition that isolates a minority of nodes
   Reveal Solution Discussion Select an answer first
4. 18application · medium

   A developer is explaining to a client why a simple majority vote is insufficient for a blockchain network where nodes may be compromised. Which statement correctly captures the core challenge of the Byzantine Generals Problem?

   • AThe primary node must be trusted, otherwise the entire network cannot reach consensus.
   • BNetwork latency can cause honest nodes to receive messages in different orders, leading to temporary disagreements.
   • CNodes may crash and stop responding, so the system must wait for a timeout before proceeding.
   • DFaulty nodes may send conflicting or false information, making it impossible for honest nodes to agree on a single truth without a protocol that tolerates such behavior.
   Reveal Solution Discussion Select an answer first
5. 19application · medium

   A blockchain startup is choosing between Tendermint and HotStuff for a new permissioned network. They expect up to 10% of validators to be Byzantine and need to minimize the number of message rounds per consensus decision. Which protocol is more suitable and why?

   • ANeither can tolerate 10% Byzantine validators
   • BTendermint, because it has a simpler two-round voting process
   • CBoth are identical in round complexity
   • DHotStuff, because it uses a linear chain of rounds and reduces communication rounds per decision
   Reveal Solution Discussion Select an answer first
6. 20foundation · medium

   How do BFT mechanisms contribute to blockchain consensus?

   • AThey increase the block size to accommodate more transactions.
   • BThey allow any node to create a new block without validation.
   • CThey reduce the energy consumption of the network.
   • DThey ensure that all nodes have the same blockchain history even if some nodes are malicious.
   Reveal Solution Discussion Select an answer first