Merkle Tree-Based Transaction Verification BDC Practice Questions (Page 4)

Questions 16–20

1. 16foundation · easy

   How is the Merkle root derived from the leaf nodes of a Merkle tree?

   • ABy concatenating all leaf hashes and then hashing the concatenation once.
   • BBy hashing all leaf nodes together at once.
   • CBy taking the first leaf hash and hashing it repeatedly with each subsequent leaf.
   • DBy recursively hashing pairs of sibling nodes until a single hash remains.
   Reveal Solution Discussion Select an answer first
2. 17foundation · easy

   What is the purpose of concatenating two child hashes before hashing them to form a parent node?

   • ATo encrypt the child hashes so they cannot be reversed.
   • BTo ensure the parent hash depends on both child hashes and their order.
   • CTo sort the child hashes in alphabetical order.
   • DTo reduce the size of the parent hash compared to the children.
   Reveal Solution Discussion Select an answer first
4. 18expert · medium

   A developer is implementing a Merkle tree for a block with 6 transactions. The tree must be built correctly to ensure tamper-evidence. Which statement about the root derivation is true?

   • AThe root is the hash of the concatenation of all six leaf hashes.
   • BThe root is the hash of the first leaf only.
   • CThe root is computed by hashing pairs of leaves, then hashing the resulting parent hashes, repeating until one hash remains.
   • DThe root is the XOR of all leaf hashes.
   Reveal Solution Discussion Select an answer first
5. 19application · medium

   An auditor wants to prove that a historical block's transaction list has not been altered since it was mined. The auditor has the block header containing the Merkle root. Which action provides the strongest evidence of tamper-evidence?

   • AConfirm that the block is referenced by the next block's header.
   • BRecompute the Merkle root from the current transaction list and compare it to the stored root.
   • CCheck that the block's timestamp is older than the current time.
   • DVerify the block's hash is less than the network difficulty target.
   Reveal Solution Discussion Select an answer first
6. 20expert · hard

   A developer is implementing a Merkle proof for a transaction in a tree with 16 leaves. The transaction is at leaf position 10 (0-indexed). The developer accidentally includes the sibling hashes in reverse order (from root to leaf) in the proof. What will happen when a verifier processes the proof?

   • AThe verifier will still compute the correct root because hashing is commutative
   • BThe verifier will accept the proof because the same hashes are used
   • CThe verifier will compute a different root and reject the proof
   • DThe verifier will detect that the proof is for a different transaction
   Reveal Solution Discussion Select an answer first