Blockchain basics Exam Questions And Answers Verified Questions| 100% Solved A+ Pass

Blockchain basics Exam Questions And Answers Verified Questions| 100% Solved A+ Pass 2 informal definitions of blockchain--what are they? - Answer- blockchain: the ledger (the way the data is stored) Blockchain: a system for maintaining a distributed ledger (ledger=blockchain) What does it mean to say that in a Blockchain network, the ledger is distributed? - Answer- The ledger is distributed, meaning that each node in the network has a copy of the ledger. There is no central authority in charge of the ledger. The data is shared. What does a block hold (simplified) - Answer- Data: specific to each blockchain Hash: identifies a block based on block contents (a fingerprint) Hash of previous block in the blockchain: creates the chain A blockchain is a type of ________, and a _______ is just a record of events - Answer- ledger What is a hash function? - Answer- A hash function is a function that takes in a unique input (and this input can be essentially anything--text file, web page, a string) and produces a unique output based on that input How is the hash of a block produced? - Answer- Each block in the blockchain has a hash value that is produced by inputting the data in the block and the hash of the previous block in the chain to produce a hash value. What is the role of a hash value on a block? - Answer- The hash value acts as a fingerprint for the block because the hash value produced is unique to that block because it was uniquely produced from the two inputs given (block data and hash of previous block). What if someone were to change the data in the second block in a long blockchain? - Answer- Someone else could rehash block number 2 and see that the hash produced does not match the hash value associated with the block. This is because the hash is unique to the data of the block and the hash of the previous block. Because of this, if the hacker wanted to modify the data in block number 2, and have it not be obvious that the block has been tampered with, they would need to recalculate the hash value of block 2. But, there is another issue with doing this. If the hacker was to modify the hash of block number 2, they would also need to modify that previous hash of block number 3 so that the chain is not broken, and make the previous hash of block 3 match the new hash of block 2. But, if the previous hash of block 3 is modified, then we arrive to the same issue we found when we modified the data of block 2: the hash value (produced from the inputs of the data and hash of the previous block) would no longer match what the hash associated with the block. Therefore, if the hacker modified the contents of block 2, they would have to rehash every subsequent block in the chain. How is blockchain immutable - Answer- one cannot change the data in a block without having to rewrite the data in every single block in the chain and not break the chain How would we check if two people agree on the record of events? - Answer- Compare the hash values of each of their final blocks. If they are not exactly the same, they have a different record of events. This is because the hash of a block is dependent on every single piece of data contained in the blockchain. The hash of a block is dependent on ... - Answer- every single piece of data contained in the blockchain Because no one "owns" the ledger, there needs to be a mean for everyone to come to an agreement on what updates to make to the ledger. We call this the __________ ___________ - Answer- consensus protocol Consensus protocol is the means that we make sure that transactions are: - Answer- maintained in the same order authentic (and to reject the bad transactions) What is bitcoin's consensus protocol? - Answer- mining What is the difference between a public and private blockchain? - Answer- Public: anyone can participate in a public Blockchain because it is open-source and public to all. Private: permission is required to participate in the Blockchain. Blockchain helps get ride of intermediaries. How? - Answer- With the introduction of Blockchain, we no longer need intermediaries to authenticate our transactions. What are smart contracts? - Answer- Simple programs that are stored on the blockchain and can be used to automatically execute actions (by writing to the blockchain) based on certain conditions What is the function of smart contracts? - Answer- The program (or programs) that interact with the blockchain (ledger) What can you use blockchain for in the real world? - Answer- Enable distributed, autonomous marketplaces Reduce friction in business transactions and reconciliations Securely maintain and share decentralized records Track the provenance of products and materials from its origin (farm, factory) to destination