EC-Council BDC (312-81) Certification Sample Questions
The purpose of this Sample Question Set is to provide you with information about the EC-Council Blockchain Developer Certification exam. These sample questions will make you very familiar with both the type and the difficulty level of the questions on the 312-81 certification test. To get familiar with real exam environment, we suggest you try our Sample EC-Council BDC Certification Practice Exam. This sample practice exam gives you the feeling of reality and is a clue to the questions asked in the actual EC-Council Blockchain Developer Certification (BDC) certification exam.
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EC-Council 312-81 Sample Questions:
01. A Corda transaction must carry the compiled contract code and a zipped copy of the governing legal terms. How are these files included?
a) As attachments, referenced in the transaction by hash
b) Through an oracle-signed command
c) As fields of an output state that the transaction creates
d) As input states that the transaction consumes and then re-issues
02. A Solidity withdraw function sends Ether to the caller and only afterward sets the caller's balance to zero. A reviewer asks the developer to apply the standard ordering pattern for this function.
Which change does the reviewer want?
a) Compare block.timestamp to a deadline before sending
b) A proxy pattern, so the function can be replaced after an incident
c) Check tx.origin so only the account owner can call it
d) Checks-Effects-Interactions: zero the balance first, then make the external transfer
03. A team evaluates a scaling design: a separate EVM-compatible chain with its own validators and consensus protocol, connected to Ethereum by a two-way bridge. It does not post its transactions or state changes back to Ethereum, and contracts written for Ethereum run on it unchanged.
Where does this chain's security come from?
a) From Ethereum, because it runs the same EVM and contract code
b) From its validator set alone, so Ethereum does not backstop a failure of that set
c) From Ethereum, through the two-way bridge that links the two chains
d) From fraud proofs that anyone can submit to Ethereum in a challenge window
04. A telecom operator deploys a new Corda node to join an existing roaming-settlement network. What must happen before the node can transact with other members?
a) It must obtain a certificate signed by the network's doorman
b) It must stake the network's native token with the notary cluster before it sends its first transaction
c) It must generate a fresh key pair for each transaction and announce those keys to its counterparties
d) It must download the transaction history from existing nodes and validate those blocks
05. An aircraft lessor and an airline record a lease on Corda as a state holding the monthly rate. The two parties renegotiate and agree a lower rate.
How does the CorDapp record the new rate on the ledger?
a) The notary updates the lease state in place after checking both parties' signatures
b) The lessor's node edits its vault copy, signs the change and syncs it to the airline
c) A reference state carrying the new rate is attached to the existing lease
d) A transaction consumes the current lease state and outputs a new version, and the old one becomes historic
06. In a securities-lending CorDapp, a compliance bank maintains a KYC state for each borrower. Every loan transaction must use that KYC data and confirm it is current, but the loan must not consume or update the KYC state.
How should the developer include the KYC state?
a) As an output state that the borrower's node signs
b) As a reference state in each loan transaction
c) As an input to each loan transaction that also outputs an identical copy of it
d) Through an oracle-signed KYC command
07. In Hyperledger Fabric's execute-order-validate flow, what does an endorsing peer do when it receives a client's transaction proposal?
a) Signs the proposal and forwards it to the ordering service without executing the chaincode
b) Passes the proposal to the channel's anchor peer, which runs the chaincode for its organization
c) Simulates it and returns a signed read-write set without updating the ledger
d) Executes the chaincode, writes the results into its world state and then forwards the proposal to the other peers
08. On a new Fabric channel, peers within each organization discover one another, but no peer has learned about any peer in the other organization. What should be defined in the channel configuration to fix this?
a) An anchor peer for each member, so gossip can reach across the member boundary
b) A Fabric CA for each organization
c) A leader peer per organization, so it pulls blocks from the orderer
d) A private data collection that includes both organizations, so their peers share data through gossip
b) A Fabric CA for each organization
c) A leader peer per organization, so it pulls blocks from the orderer
d) A private data collection that includes both organizations, so their peers share data through gossip
09. Three auto-parts manufacturers run a Fabric channel with chaincode that records warranty claims. They agree that a claim transaction should count as valid only when peers belonging to Org1 and Org2 have both executed the chaincode and signed the results.
What should they configure?
a) A Raft consenter set with one ordering node hosted by each of the two organizations
b) An endorsement policy requiring peers of both Org1 and Org2
c) A local MSP on each organization's peers
d) A channel Writers policy that lists the clients of Org1 and Org2
10. Two banks use a Corda interest-rate-swap CorDapp. A rate oracle must sign each transaction to attest the benchmark rate fixing, but the banks do not want the oracle to see the notional amounts or other states in the deal.
What should the proposing node do?
a) Encrypt the output states with the other bank's key before sending the transaction
a) Encrypt the output states with the other bank's key before sending the transaction
b) Have the contract's verify function fetch the rate from the oracle during verification
c) Tear off the components the oracle does not need, so it signs a filtered view that still commits to the whole transaction
d) Send the full transaction to the oracle, which then removes the notional amounts before it signs
Answers:
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Question: 01 Answer: a |
Question: 02 Answer: d |
Question: 03 Answer: b |
Question: 04 Answer: a |
Question: 05 Answer: d |
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Question: 06 Answer: b |
Question: 07 Answer: c |
Question: 08 Answer: a |
Question: 09 Answer: b |
Question: 10 Answer: c |
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