Network Layer, Consensus, Smart Contract, and Node Security Best Practices BDC Practice Questions (Page 1)

Questions 1–5

1. 1foundation · easy

   In threat modeling for a blockchain system, what is the primary purpose of identifying assets?

   • ATo determine the cost of the system
   • BTo comply with legal requirements
   • CTo prioritize which components need the most protection
   • DTo create a marketing plan
   Reveal Solution Discussion Select an answer first
2. 2application · medium

   A blockchain network operator is concerned about Sybil attacks on a permissioned network. The network uses a reputation system for validators, but an attacker has created many fake identities to gain influence. Which additional control would be most effective in mitigating Sybil attacks?

   • ARely on the reputation system alone to filter out fake identities.
   • BIncrease the number of validators to make the network more decentralized.
   • CUse a simple proof-of-work requirement with a low difficulty level.
   • DRequire validators to stake a significant amount of the network's native token, making it costly to create many identities.
   Reveal Solution Discussion Select an answer first
4. 3application · medium

   A developer is writing a smart contract that accepts user input for a withdrawal amount. The contract currently does not validate the input, and a user could potentially withdraw more than their balance. Which best practice should be applied to prevent this?

   • AAdd a require statement that checks the withdrawal amount is less than or equal to the user's balance before processing.
   • BCast the withdrawal amount to a smaller integer type to truncate any excess.
   • CRely on the token contract to reject invalid withdrawals.
   • DUse a try-catch block to handle any errors during the withdrawal.
   Reveal Solution Discussion Select an answer first
5. 4application · medium

   A blockchain network is experiencing a DDoS attack targeting its public RPC endpoints. The attack is overwhelming the nodes with requests, causing legitimate users to be unable to access the network. Which mitigation strategy would be most effective in maintaining service availability?

   • APlace a rate-limiting reverse proxy in front of the RPC endpoints and use a CDN to absorb and filter malicious traffic.
   • BDisable the RPC endpoints temporarily to stop the attack.
   • CIncrease the node's maximum connections to allow more requests through.
   • DMove the RPC endpoints to a different port and hope the attackers do not find it.
   Reveal Solution Discussion Select an answer first
6. 5foundation · easy

   Which network-level attack on a blockchain involves an adversary creating a large number of fake identities to gain disproportionate influence over the network?

   • ADistributed denial-of-service (DDoS) attack
   • BSybil attack
   • CEclipse attack
   • DReplay attack
   Reveal Solution Discussion Select an answer first