Bitcoin and Bitcoin Blockchain Architecture BDC Practice Questions (Page 10)

Questions 46–49

1. 46foundation · easy

   What is a soft fork in Bitcoin?

   • AA change that is backward-compatible, where old nodes still accept new blocks
   • BA change that creates a new cryptocurrency with a different ticker
   • CA temporary split that resolves automatically without any rule change
   • DA change that requires all nodes to upgrade or they will be left behind
   Reveal Solution Discussion Select an answer first
2. 47application · medium

   A developer wants to create a Bitcoin transaction that can only be spent after a certain block height, using a time lock. Which Bitcoin Script opcode should be used in the locking script?

   • AOP_CHECKLOCKTIMEVERIFY (CLTV)
   • BOP_RETURN
   • COP_HASH160
   • DOP_CHECKMULTISIG
   Reveal Solution Discussion Select an answer first
4. 48application · medium

   A developer is inspecting a Bitcoin block header and wants to verify that the block's transactions have not been tampered with. Which field in the block header should the developer compare against a locally computed value?

   • AThe previous block hash, which links the chain.
   • BThe nonce, which is adjusted during mining.
   • CThe Merkle root, which is computed from all transactions in the block.
   • DThe timestamp, which records when the block was created.
   Reveal Solution Discussion Select an answer first
5. 49application · medium

   A developer is building a Bitcoin wallet that must show users the exact amount of bitcoin they can spend from a given address. The wallet has access to a full node's transaction index. Which data structure should the wallet query to determine the spendable balance?

   • AThe set of unspent transaction outputs (UTXOs) that reference the address
   • BThe transaction history of the address from the block index
   • CThe block header's nonce value
   • DThe Merkle root of the latest block
   Reveal Solution Discussion Select an answer first