1] What do you understand by Block chain?  The block chain is a redistributed distributed database of immutable records. The technology was discovered with the invention of Bit coins the 1st crypto currency 2] What is the principle of Block chain Technology?  It allows the information to be distributed among the users while not being traced. 3] What are the various types of Block chains?  Block chains are of 3 types: • Public • Private • Consortium 4] Name the 2 kinds of records that are present within the Block chain Database?  These records are block records and transactional records. Each these records will simply be accessed, and also the neatest thing is, it’s doable to integrate them with one another while not following the complicated algorithms. 5] What do you mean by blocks within the block chain Technology?  Blockchain consists of a list of records. Such records are kept in blocks. These blocks are successively linked with different blocks and therefore represent a sequence known as Blockchain. 6] How is a block recognized within the Blockchain approach?  Every block during this online ledger essentially consists of a hash pointer that acts as a link to the block that is before it, transaction knowledge and in fact a stamp of time. 7] What is the difference between ethereum and bit coin block chain?  A block chain is a distributed peer-to-peer network. It offers peers to record immutable data and transparency. The difference between bit coin and ethereum is their approach.  Ethereum, being the 2nd generation block chain solution improves on bit coin in almost every possible way.  The main difference is how they are trying to solve the industry problem. Conceptually, bit coin is a digital currency.  Whereas ethereum is about smart contracts. Ethereum is also energy efficient as it uses Proof-of-Stake (PoS) consensus algorithm compared to bit coin’s Proof-of-Work (POW). This also makes ethereum more scalable compared to bit coin. 8] State an example of asymmetric encryption Algorithm?  The example of asymmetric is RSA 9] State difference between proof of stake and proof of work.  Proof of Work • The possibility of Mining a Block depends upon the amount of work a miner does • Takes more energy than proof of stake  Proof of Stake • Stakeholder Validate new block by but utilizing their share of coin on the network • The first example of proof of stake is peer coin 10] What are some of the widely used cryptographic algorithms?  Some of the most usually used algorithms are RSA 11] What is public block chain? Give examples.  A public block chain is public in nature. They are entirely decentralized where anyone can read, write and join. No central authority controls the blockchain. Also, all the data can be validated as data once are written cannot be altered. Key examples of public blockchains include bit coin and ethereum. 12] What are the types of consensus algorithms?  There are many types of consensus algorithms or techniques out there. The most popular consensus algorithm includes Proof-of-Work (POW) • Proof-of-Stake(PoS) • Delegated Proof-of-Stake(DPoS) • Proof-of-Authority(PoA) • Proof-of-Elapsed Time(PoET) • Byzantine Fault Tolerance 13] What is Consensus algorithm?  Consensus algorithm is the method of gaining consensus on a change of a data over the system or distributed network. Consensus algorithms are heavily used in blockchains as they enable the network of unknown nodes to reach consensus on the data that is being stored or shared through the blockchain. Some of the most popular consensus algorithms include Proof-of-Stake(PoS) and Proof-of-Work(PoW) 14] Is it possible to switch the data once it’s written in an exceeding block?  No, it’s impossible to do so. Just in case any modification is needed, the organization merely has to erase the knowledge from all different blocks too. Because of as a result of no different reason than this, knowledge must be given the acute care of while mistreatment this approach. 15] What are the key features/properties of blockchain?  There are many key features of blockchain. They include the following. • Immutability: The data once stored in blockchain is immutable. This gives the blockchain tamper detection property as well. • Decentralized ledger technology: The decentralized ledger technology is the most important feature of a blockchain. It can be used by a private organization or public in a variety of use-cases. • Better user anonymity: Users are relatively hidden compared to other traditional networks. • Double spending: Blockchain solves double spending problems using consensus algorithms and distributed ledger technology. 16] What are the drawbacks of blockchain?  Blockchain is not free from drawbacks or disadvantages. • Complex technology which is hard to implement and maintain • Scalable issues are still there • Network speed and transaction costs vary • Human error is still not eliminated 17] Name the common sort of ledgers which will be thought of by users in Blockchain?  These are: • Centralized Distribution • Decentralized distribution • Distributed network 18] What are the advantages of Blockchain that you simply know?  There are plenty of benefits for Blockchain: • Settlement in real time • Cost saving • Immutability • Security • User Pseudonymity 19] What is the primary benefit of immutability?  There are plenty of benefits of immutability but the foremost basic benefit is increased efficiency. 20] Name some widespread platforms for developing blockchain applications.  After the event of bit coin, numerous blockchain platforms started arising. Ethereum came right once the evolution of Bit coins, and is one in all the favoured public platforms for building. Blockchain primarily based applications.  Then there’s a Hyperledger community for building enterprise-based solutions. Also, Qtum, IOTA, EOS are a number of the widely used platforms for building Blockchain. 21] What are the businesses benefits of blockchain?  Businesses can make a lot of benefit from the use of blockchain. They are • Audibility • Efficiency • Transparency • Traceability • Feedback • Security 22] Can the data stored in a block modified once it is written? If so, why?  The data stored on the blockchain is protected with proper encryption using a digital signature. This makes the data written in a block as a one-time process only. It cannot be altered by any means. 23] Each and every block of Blockchain consist of what elements?  Each and every block include three major parts • A hash pointer to the previous block • Timestamp • List of transactions 24] Which one Bit coin or Ethereum was the first distributed blockchain implementation?  The answer is bit coin as it was found on 8th August 2008 25] What are the forms in which Blockchain can be stored?  The blockchain is a distributed ledger which can be stored in 2 Forms • A flat file • A Database 26] In Blockchain, blocks are linked in what series?  In Blockchain Blocks are arranges within the Backward to the previous block series. 27] Is it true that a block in the blockchain can never have more than one parent block?  Yes, it’s true that Blockchain can never have a parent Block. Each and each block is independent in Blockchain 28] State an example of asymmetric encryption Algorithm?  The example of asymmetric is RSA 29] What are some of the widely used cryptographic algorithms?  Some of the most usually used algorithms are • RSA • Triple DES • Blowfish • Two fish • AES 30] What are the various approaches employed in attacking the RSA algorithm?  There square measure totally different approaches employed in assaultive the RSA algorithm: • Brute force: It involves all potential secret keys • Mathematical attacks: In mathematical attack, we tend to square measure mistreatment totally different techniques, that is analogous in the effort to issue the merchandise of 2 primes 31] What are the benefits of blockchain to ensure proper safety?  There are six key principles that can ensure proper safety and allow organizations to create appropriate transactional records. • Auditing • Securing applications • Database security • Digital workforce training • Proper testing methods • Continuity planning. 32] What is block identifiers?  Every block on a blockchain has a unique identifier. It is the hash value that acts as a unique identifier. This means that no two blocks identifiers will be identical. 33] What is a node?  A node is essentially a computer, connected to the network, which processes transactions. 34] Why would you have a private network?  There are many reasons, but mainly because of data privacy, distributed database, permissions control and testing. 35] How can you easily see details about transactions and blocks?  Using blockchain explorers like etherscan.io or live.ether.camp 36] What is Metamask?  Metamask is a tool which helps you to easily interact with the Ethereum networks in your browser 37] What is Remix?  An online tool for developing, testing and deloying contracts. It’s great for quickly building and testing lightweight contracts but not for more complex ones. 38] Explain Call data  It can be thought of as the call stack. It is temporary, non-modifiable, and it stores EVM execution data. 39] What is the ABI used for?  ABI is a description of the public interface of a contract, which is used by DApps for invoking the contract. 40] What is the difference between call and send?  Send sends a transaction and costs money while .call queries the state of the contract. 41] What is encryption? What is its role in Block chain?  Data security always matters. Encryption is basically an approach that helps organizations to keep their data secure. Cryptography-top blockchain interview questions- eureka the encrypted data is encoded or changed up to some extent before it is sent out of a network by the sender and only authorized parties can access that information. In Blockchain, this approach is useful because it simply adds more to the overall security and authenticity of blocks and helps to keep them secure. 42] How does a block is recognized in the Blockchain approach?  Every block in this online ledger basically consists of a hash pointer which acts as a link to the block which is prior to it, transaction data and in fact a stamp of time. 43] What type of records is kept in a Blockchain? Is there any restriction on same?  There is no restriction on keeping records of any sort within the Blockchain approach. Industries are using Blockchain for securing all kinds of records. 44] Explain the importance of blind signature and the way it’s useful?  It is a type of digital signature within which the content of a message is disguised (blinded) before it’s signed. The ensuing blind signature may be publically verified against the first, unblinded message within the manner of a daily digital signature.  Blind signatures are generally used in privacy-related protocols where the signer and message author are totally different parties. Examples include cryptographic election systems and digital money schemes. 45] What is a security policy?  A security policy defines what exactly needs to be secured on a system. It bounds a network user under some core protocols that they all must agree and follow to enhance the overall security. When it comes to information or financial records of an organization, multiple security policies are implemented than just one. 46] Why is Blockchain a trusted approach?  Blockchain can be trusted due to so many reasons. • Its compatibility with other business applications due to its open-source nature. • It really doesn’t matter what type of business one owns, Blockchain can easily be considered. 47] A distributed digital ledger is used for recording transaction in Blockchain. What does the system rely on?  The system relies on the network servicing protocol and the nodes of the network. 48] What are the benefits of the distributed ledger?  As we know Blockchain is a public ledger and it contains the information like all the participants and all the digital transactions that have ever been executed. There are many advantages of public ledger, they are: • Fraud prevention: In Blockchain data is decentralized and ledger data distributed across the multiple nodes. If there is any unauthorized changes to ledger data, Blockchain technology responds very well and prevents it. Ledger data can’t be changed and it prevents any kind of frauds. • Get rid of multiple ledgers: Blockchain distributed ledger technology helps organizations in maintaining all their transaction data into a single ledger, it reduces the complications of having multiple ledgers. • Ownership Assurance: Distributed ledgers can enable new ways of assuring ownership to the digital assets, goods and intellectual property. • Eliminates Mediatory: Blockchain eliminates mediatory and reduces the transaction time for settlements with keep track of everything in ledger in a secured way. 49] Explain Private block chains?  A private blockchain is a permission. One cannot join it unless invited by the network administrators. Participant and validator access is restricted. 50] Explain Consortium Block chains?  A consortium blockchain is often said to be semi-decentralized. It, too, is permission but instead of a single organization controlling it, a number of companies might each operate a node on such a network. -pranjali sawaikar SRIEIT]]>