Showing posts with label blockchian. Show all posts
Showing posts with label blockchian. Show all posts

November 04, 2022

Top 20 Amazon Managed Blockchain Questions and Answers


With the help of popular open-source frameworks, you can create and administer scalable private networks with Amazon Managed Blockchain, a fully managed service that lets you join public networks. The overhead involved in setting up a network or joining one already exists, and Amazon Managed Blockchain automatically expands to meet the needs of thousands of apps processing millions of transactions. Managed Blockchain makes it simple to administer and maintain your blockchain network once it is up and running. It keeps track of your certificates and makes it simple to welcome new users to the network.


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Ques: 1). How is Amazon Managed Blockchain accessed?


The AWS Management Console, AWS Command Line Interface (CLI), and AWS Software Development Kit all provide access to Amazon Managed Blockchain (SDK).

Use the open source Hyperledger Fabric CLI and SDK to communicate with the Hyperledger Fabric components provided and managed by Amazon Managed Blockchain, such as the ordering service, certificate authority, and peer nodes. You construct a VPC PrivateLink endpoint for your network to access the endpoints that Amazon Managed Blockchain offers for accessing these services. The version of Hyperledger Fabric stated in your network must be used along with a compatible version of the CLI and SDK for Hyperledger Fabric.

Your client utilises a WebSocket or HTTP connection to a peer node endpoint in Managed Blockchain to communicate with Ethereum smart contracts. Only your AWS Account has access to your node endpoint. The client communicates with your node on the Ethereum network using normal JSON-RPC API techniques to query and send transactions.

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Ques: 2). What is Amazon Managed Blockchain capable of?


Using the open-source frameworks Hyperledger Fabric and Ethereum, you can quickly join public networks or build private networks spanning several AWS accounts using Amazon Managed Blockchain. These blockchain systems let network users safely exchange money and data on a decentralised, unchangeable record. Additionally, you may set up your network's voting procedures so that users can democratically run it (i.e., voting on who to invite to join).

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Ques: 3). A blockchain network is what?


A trusted central authority is not required to ensure that transactions are secure and validated thanks to the blockchain technology, which enables the development of apps where numerous parties can record transactions.

This is made possible by blockchain because it creates a peer-to-peer network (also known as a blockchain network) where each user has access to a shared ledger where the transactions are recorded. By design, these transactions are immutable and subject to independent verification.

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Ques: 4). I want to join the blockchain network, how can I invite other AWS accounts?


You can submit a request to the present users of the blockchain network asking them to approve inviting a different AWS account to join. The other AWS account will be invited to join the network if the proposal is accepted based on the network's voting regulations.

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Ques: 5). How can I connect with my Amazon Managed Blockchain resources using the open source Hyperledger Fabric CLI or SDK running on a client node?


You may use the free Hyperledger Fabric CLI or SDK to setup them and communicate with the peer nodes, ordering service, and certificate authority (CA) that were generated for your network using Hyperledger Fabric. By leveraging a VPC PrivateLink endpoint that you construct in your VPC, Amazon Managed Blockchain makes the endpoints for these components accessible. To access this VPC PrivateLink endpoint, the Amazon EC2 instance or other resource using the Hyperledger Fabric CLI or SDK needs a route.

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Ques: 6). How do I get started with Amazon Managed Blockchain?


To get started with Amazon Managed Blockchain, go to the AWS Management Console and click on Amazon Managed Blockchain. Click on "Create a network" or “Join a network”. Follow the network creation wizard to create your first network and member, and then invite other AWS accounts to join. Alternatively, follow the join network wizard to join a public network, and then provision nodes to interact with the network.

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Ques: 7). Owns that resource the account that builds an Amazon Managed Blockchain network?


An Amazon Managed Blockchain network is a decentralised resource in which various AWS accounts have equal ownership stakes in accordance with the voting guidelines established at the network's inception. The Approval Threshold Policy type allows for the distribution of governance across several members when they join the network, even though an original AWS account builds it. The network will continue to function among the surviving members even if the original member exits.

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Ques: 8). What elements make up Hyperledger Fabric?


An Amazon Managed Blockchain for Hyperledger Fabric builds and maintains the necessary network components on your behalf. The ordering service, certificate authority, and peer components all come together to form a Hyperledger Fabric network.

You utilise an open source Hyperledger Fabric CLI or SDK from a client host that you construct and administer to communicate with these components.

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Ques: 9). How do I limit who may access the resources I have on Amazon Managed Blockchain?


In order to identify users in each membership and assess their network rights, Hyperledger Fabric on Managed Blockchain requires certificates. With the help of the Hyperledger Fabric certificate authority, you may create and manage these users. JSON-RPC requests to Ethereum nodes on the Managed Blockchain are verified using Signature Version 4 (SV4).

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Ques: 10). What rights does the administrator user have when adding a network member?


The first user in your Hyperledger Fabric membership is the admin account that you set when creating your network member. The username and password may be used to add other users to your membership and register this user with your Hyperledger Fabric certificate authority. Additionally, the admin user has the ability to install and run chaincode programmes as well as construct channels on the network.

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Ques: 11). What distinguishes Amazon Quantum Ledger Database (QLDB) from Amazon Managed Blockchain?


A ledger database called QLDB was created specifically for clients that needed to keep a comprehensive and verifiable history of data changes in an application that they owned and centrally managed. Not a blockchain technology, Amazon QLDB. Instead, blockchain technologies concentrate on making it possible for several parties to do business and transfer data safely in a decentralised manner, without the need for a reliable centralised authority. A network's members can make and endorse transactions, and each member owns an independently verified copy of an immutable ledger. Amazon Managed Blockchain is a fully managed blockchain service that enables multiple parties to transact and share data directly and securely without the need for a central, trusted authority.

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Ques: 12). How can I remove a network from Amazon Managed Blockchain?


Once the final participant in a network deletes their membership, the network is terminated by Amazon Managed Blockchain. If you've formed a blockchain network with several members in your AWS account, the network will be terminated after all of the members have been removed. If you are a member of a blockchain network that contains memberships that you do not control, the network will only be eliminated when the final participant does so. If you remove a member from a network but there are still other members present, the network will continue. If a founding member departs a network, there will be adjustable ways to end it once Amazon Managed Blockchain is broadly accessible.


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Ques: 13). I want to boost the availability of my blockchain components, can I establish numerous peer nodes?


For high availability, the Standard Edition allows you to build up to three blockchain peer nodes in each membership across different Amazon EC2 availability zones. For each membership in the Starter Edition, two peer nodes can be created. You may set up as many as 50 nodes per AWS account across different Amazon EC2 availability zones for Ethereum on Amazon Managed Blockchain.

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Ques: 14). : What open source blockchain frameworks is supported by Amazon Managed Blockchain?


The open source Hyperledger Fabric and Ethereum frameworks are supported by Amazon Managed Blockchain.


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Ques: 15). What is the cost of Amazon Managed Blockchain?


Amazon Managed Blockchain has no initial contract. You just pay an hourly fee (paid per second) for your network membership, peer node storage, and data you send to the network while using Hyperledger Fabric on Amazon Managed Blockchain. The Standard Edition and the Starter Edition are the two editions that Amazon Managed Blockchain offers, and each edition has a different hourly membership charge. You also pay regular data transmission charges. You will require a VPC PrivateLink endpoint that is separately paid in order to communicate with your Amazon Managed Blockchain services. With Amazon Managed Blockchain for Ethereum, you can build nodes and connect them to open Ethereum networks. You are charged for the node, node storage, and the number of Ethereum requests you make.


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Ques: 16). What distinguishes the Starter Edition and Standard Edition network types of Amazon Managed Blockchain?


Starter Edition and Standard Edition are the two network types that Amazon Managed Blockchain offers. Each kind has a distinct hourly membership charge and is designed for a certain set of use scenarios.

For test networks and smaller production networks, there is a network called Amazon Managed Blockchain Starter Edition. In comparison to the Standard Edition, it features the following characteristics: A network can have up to 5 members and 2 peer nodes per member. The peer node kinds that are available are bc.t3.small and bc.t3.medium. The transaction throughput and availability of the ordering service are lower in a Starter Edition network than in a Standard Edition network.

The network for the Amazon Managed Blockchain Standard Edition is intended for use with production networks. It differs from the Starter Edition in a number of ways, including the ability to have 3 peer nodes and a limit of 14 users per network. Peer nodes can use the instance types from the bc.t3, bc.m5, and bc.c5 families. The transaction throughput and availability of the ordering service are better in a Standard Edition network than they are in a Starter Edition network.


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Ques: 17). Do my blockchain components experience any downtime for maintenance?


Ethereum nodes are always online. When we deploy security updates, which we normally do monthly or as needed, Hyperledger Fabric peer nodes will be down for less than a minute. Your Personal Health Dashboard will let you know when maintenance is going to be performed. As only one peer per member will be patched at a time, you can construct numerous peers to reduce this downtime. It is often advised to have numerous peers for high availability.


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Ques: 18). In my Hyperledger Fabric network, how can I establish a channel?


A Hyperledger Fabric channel is a secret "subnet" of communication between two or more specified network users, for the purpose of carrying out private and confidential transactions. Every transaction on the blockchain network takes place on a channel, where each person involved must be verified and given permission to do business.

Using the open source Hyperledger Fabric CLI or SDK and the APIs provided on your Hyperledger Fabric resources, you may add a new channel to your Amazon Managed Blockchain network. A genesis block for the channel ledger, which holds configuration data about the channel policies, members, and anchor peer nodes, is created when you call the configuration system chaincode.


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Ques: 19). How can I get access to the Hyperledger Fabric endpoints on the parts that Amazon Managed Blockchain manages?


A VPC PrivateLink endpoint must be created in the VPC from which you wish to connect the network in order to access the endpoints on the Hyperledger Fabric components maintained by Amazon Managed Blockchain, such as the Hyperledger Fabric certificate authority, ordering service, and peer nodes. From the VPC panel, Amazon Managed Blockchain console, AWS CLI, or AWS SDK, you may build a VPC PrivateLink endpoint. Use the VPC Endpoint Service Name shown in the Amazon Managed Blockchain network specifications when building your endpoint. You just need to build one VPC PrivateLink endpoint, not one for each member, if you've created them all in the same AWS account. Additionally, in order to get support for suggested transactions, your client will be able to communicate with peer nodes from other network participants.

Please be aware that any VPC PrivateLink endpoints you establish or use will incur a separate fee.


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Ques: 20). How can I introduce apps written in chaincode into the Hyperledger Fabric network?


Chaincode, often known as a "smart contract," is a software that generally manages business logic decided upon by network participants. Using the open source Hyperledger Fabric CLI or SDK and the APIs accessible on your Hyperledger Fabric resources, you may install and instantiate chaincode on the blockchain network. Additionally, these activities may only be carried out by admin users in your membership.


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December 23, 2019

Top 20 BlockChain interview Questions & Answers

Ques: 1. What are the differences between a traditional database and Blockchain database?

Ans: The difference between a traditional database and blockchain database is as follows:

1. Storage of Records: In a traditional system the records are centralized whereas in Blockchain the records are decentralized.

2. Operations Done: In a Blockchain system, you can only perform insert operations whereas in the traditional system you can read, edit, create and update the transactions.

3. Validations of transactions: You can validate any number of transactions on the network in a Blockchain whereas in the traditional database only specific nodes are allowed to validate the transactions.

Ques: 2. What are Ethereum Smart Contracts and in which language is Ethereum written?

Ans: A Smart Contract is a set of program that gets automatically executed on meeting the certain requirements of Blockchain. Ethereum is generally written in Solidity programming language.

Ques: 3. What are the types of record that can be kept in Blockchain?

Ans: In Blockchain, you can keep any number of records. Few of the records that can be kept in the blockchain ledger are:

1. Medical Transactions and history

2. The identity of numerous persons

3. Several numbers of events that take place in an organization and organizational records

4. Management records of companies that can be accessed from anywhere in the world with proper secure transactions

5. Documents that are to be kept at high-level security

Ques: 4. What are the benefits of Blockchain in business?

Ans: European Banks have already launched their projects to use this technology. The international payments system VISA has also joined them. Blockchain gives several advantages to the financial sector some of which are listed below:
  • Money Transfer will become faster and cheaper payments are possible and significantly reduce their costs. 
  • With the help of the Smart Contracts are computer programs which facilitate to verify and negotiation of the agreement. 
  • In stock exchange Blockchain can remove brokers as intermediaries and decentralize the stock exchange system.

Ques: 5. What are the basic components of the Blockchain Ecosystem?

Ans: There are four basic components of Blockchain ecosystem as explained here:
  • Shared Ledger:  It is a distributed data structure shared among peers managed inside Node application. 
  • Node Application: Each of the nodes is installed and run on a computer to become a part of the blockchain network. 
  • Virtual Machine: Here the implementation of instruction takes place and every participant runs that VM. 
  • Consensus Algorithm: It is implemented as a part of node application which provides the rules for validation of transactions.

Ques: 6. How many cryptographic algorithms are used in Blockchain?

Ans: Here are some of the widely used cryptographic algorithms:
  • Triple DES: DES stands for digital encryption system which uses 3 different keys of 56 bits. 
  • RSA: It is used in several areas in the digital certificate which is a public key encryption algorithm to encrypt the information transferred on the internet. 
  • Blowfish: It is highly effective and works with great speed which encrypts the cipher messages individually. 
  • Twofish: It is similar to blowfish with keys of length 256 bits. 
  • AES: Of all algorithms, AES is the strongest encryption algorithm to breach out as it uses 192 and 256 length bit keys for heavy encryption.

Ques: 7. Can you explain pragma and provide its syntax?

Ans: Pragma is a version of Solidity that will be used by the code that is written in the solidity. For using solidity as a compiler and writing smart contracts the version should be higher than 0.4.0. Every Smart contract starts with pragma only.

Syntax: version pragma ^0.4.00.

Ques: 8. What do you mean by Merkle trees and explain its importance in Blockchain?

Ans: Also called as the hash tree, Merkle tree is the fundamental part of a Blockchain. merkle tree uses cryptographic blocks which are used to securely transact large chunks of data. Both Ethereum and Bitcoin use Merkle trees.

Ques: 9. What do you understand by 51% attack?

Ans: The blockchain is a chain of blocks that stores all transactional data in a period. Once the block enters the system it cannot be altered, and the fraudulent data would be automatically rejected by network users. However, if 51% of the miners are controlled then a group of attackers can interfere with the process of recording of new blocks. 
They can block other users transactions and reverse it also. It is also known as double spending. A network that would allow double spending could suffer a loss of confidence. Then this kind of attack is called a 51% attack.

Ques: 10. What is a block in blockchain technology?

Ans: Blocks are the storage unit of the blockchain. They are fundamental to the network, and the transactions data is stored within them. They be books with each page equivalent to a transaction. Blocks are immutable. This means if a data is recorded, it cannot be changed or deleted. Also, blocks are organized linearly in a blockchain.
A block is mined by a miner which acts to verify the transaction. This means that until a transaction is not mined, it will not be shown on the blockchain and the transaction will be deemed incomplete.

Ques: 11. What is the role of encryption in blockchain?

Ans: Encryption is an age-old technique to protect data from third parties or leak. It is the basics of data security in the modern world. Blockchain also utilizes encryption to good effect. The data before it is sent off to the receiver is encrypted. The received will only be able to unlock it as it is only meant for him. Once the receiver receives it, it is unencrypted and can be used as liked.
Blockchain also uses encryption in other ways. Also, modern blockchain solution tends to improve encryption and provide complete privacy-based experience for users.

Ques: 12. What is the difference between the standard ledger and a blockchain ledger?

Ans: The biggest difference between these two types of ledger is the decentralization that they have to offer. Blockchain ledger is decentralized which means that it offers unique capabilities such as trust, immutability, transparency, and security. Standard ledger does carry these features but is limited to certain extent.
As humans create, modify and monitor the standard ledger, there is always a chance of an error creeping in or worse a security breach. Blockchain ledger solves all the problems that standard ledger has by providing a decentralized version.

Ques: 13. What is Node Application? Explain in detail.

Ans: Node application is a computer application that a computer needs to be part of the ecosystem. Without the node application, it is not possible for a device to participate in blockchain activity.
There is different node application when it comes to the blockchain. Bitcoin, for example, uses the Bitcoin wallet application to make a computer compatible with the blockchain.
Technically, there is a service overlay network(SON) that interfaces between the blockchain and the computer. The computer needs to use the node application to read and reply in a specific manner,
Not all node application is free from restriction. Some blockchains are stick when allowing a node to join the application. It needs permission to do so.

Ques: 14. What are the different types of Consensus Algorithm? Explain each of them briefly.

Ans: There are three main types of consensus algorithm.
  1. Proof-of-Work(PoW): Proof-of-Work(PoW) is used by the most popular cryptocurrencies out there. Bitcoin, Ethereum, and Litecoin use it. It works by solving complex mathematical problems. The hash needs to be solved for the block to be mined. Once it is done, the transaction is validated, and the consensus is made.
  2. Proof-of-Stake(PoS): Proof-of-Stake(PoS) works by staking coins. The nodes need to stake a minimum amount of coins to become part of the consensus network. Once they become part, they actively take part in making decisions on the network. Unlike Proof-of-Work, PoS doesn’t require huge computational power, and hence power. 
  3. Delegated Proof-of-Stake(DPoS): Delegated Proof-of-Stake is a centralized approach to a blockchain network. In this consensus method, the stakes choose delegates which in turn validate the transactions.

Ques: 15. What is ‘blind signature’ and why is it used?

Ans: Blind Signature is a digital signature wherein all the information pertaining to a contract is made blind before it is actually agreed upon and sealed with a sign. This approach is a crucial component of cryptography and is mainly used for privacy-related protocols (for example, digital cash scheme) where the author and the signing parties are different.

Ques: 16. What are the fundamental principles in Blockchain that are used to eliminate security threats?
Ans: The fundamental principles in Blockchain that must be followed to eliminate security threats are:
  1. Auditing 
  2. Securing applications 
  3. Securing testing and similar approaches 
  4. Database security 
  5. Continuity planning 
  6. Digital workforce training

Ques: 17. What do you understand by the terms – ‘public key’ and ‘private key.’?

Ans: A public key is one which is used in cryptographic algorithms that allow all the users/peers in a Blockchain network to receive funds in their wallet. This key is essentially an alphanumeric string that is unique to a particular node or address.
A private key, on the other hand, is an alphanumeric phrase that is used in pair with a public key for encryption and decryption purposes. This key remains with a single individual who is the key generator for it. In case, anyone else gets their hand on the private key, the data within the wallet of the generator will be compromised.

Ques: 18. What do you mean by ‘off-chain’ transactions?

Ans: An off-chain transaction occurs when values are moved or placed outside the Blockchain. In this sense, it is merely a ‘transaction’ and not a ‘Blockchain transaction.’ Such transactions have no bearings on the values stored within the blocks of a Blockchain. 

Ques: 19. Explain ‘secret sharing.’

Ans: Secret Sharing is a method dedicated to protecting data integrity in Blockchain. In this method, the information or data is divided into different units and then transferred to the users on the Blockchain network. To complete the entire information, users who received the chunks of broken information must agree to share their pieces of information and combine them together.

Ques: 20. Explain a real-time blockchain use case?

Ans: Healthcare can use blockchain to their advantage. Many startups are currently working on a blockchain powered health app that lets patients store their information on the blockchain. The decentralized nature means that they don’t have to carry documents. Healthcare specialist can also take advantage of it as they can access the patient’s data anytime they want. Researchers also benefit from public blockchain where they can access large public data.