20 Hyperledger Fabric Interview Questions and Answers

Hyperledger Fabric is a popular open source framework for developing blockchain applications. If you are applying for a position that involves developing blockchain applications, you may be asked questions about Hyperledger Fabric during your job interview. Knowing how to answer these questions can help you impress the hiring manager and improve your chances of being hired. In this article, we review some of the most common Hyperledger Fabric interview questions and provide tips on how to answer them.

Hyperledger Fabric Interview Questions and Answers

Here are 20 commonly asked Hyperledger Fabric interview questions and answers to prepare you for your interview:

1. What is Hyperledger Fabric?

Hyperledger Fabric is a permissioned blockchain infrastructure, originally contributed by IBM and Digital Asset Holdings. It is a platform for distributed ledger solutions, underpinned by a modular architecture that delivers high degrees of confidentiality, resiliency, flexibility and scalability.

2. Can you explain what a blockchain network is in the context of Hyperledger Fabric?

A blockchain network is a decentralized network of computers that all have a shared ledger of transaction data. This ledger is maintained by a consensus algorithm, and each computer on the network has a copy of the ledger. Transactions are verified by each computer on the network before they are added to the ledger, and each computer has a record of all transactions that have ever been made on the network.

3. Can you give me some examples of real-world applications that use Hyperledger Fabric?

There are many potential applications for Hyperledger Fabric, as it is a very versatile platform. Some examples include:

– Supply chain management
– Identity management
– Healthcare data management
– Asset management
– Voting systems
– Financial systems

4. Can you list some of the key features provided by Hyperledger Fabric?

Some of the key features provided by Hyperledger Fabric include:

-A permissioned network with configurable levels of access
-Support for multiple channels to allow for private transactions
-Plug-and-play components for easy customization
-A modular architecture that allows for different consensus algorithms to be used
-A rich query API for data analytics

5. How do transactions work in Hyperledger Fabric?

Transactions in Hyperledger Fabric are processed by a network of nodes, each of which has a copy of the ledger. In order for a transaction to be processed, it must be signed by a validator node. Once a transaction is signed, it is broadcast to the other nodes in the network. Each node then verifies the signature and, if valid, adds the transaction to its copy of the ledger.

6. What’s the difference between private and public ledgers? Why would someone want to use one over the other?

A private ledger is a permissioned ledger, meaning that only authorized parties can access it. A public ledger is permissionless, meaning that anyone can access it. Private ledgers are typically used for confidential transactions, while public ledgers are used for transparent transactions.

7. Is there a limit to how much data can be stored on the ledger?

No, there is no limit to how much data can be stored on the ledger. The only limit is the amount of storage that is available on the server that is hosting the ledger.

8. Can you give me an example of how a query works on the ledger?

A query on the ledger is a request for information about a specific transaction or data element. For example, you might query the ledger to find out the status of a particular transaction, or to retrieve the data associated with a particular data element.

9. What are channels?

Channels are a private, shared ledger between two or more specific peers on a Fabric network. They allow for a subset of the network to transact and share data in a confidential way. By creating a channel, you are essentially creating a new subnetwork with its own ledger and smart contracts.

10. What is BFT consensus?

BFT consensus is a type of consensus algorithm that is used in distributed systems. It is based on the principle of Byzantine fault tolerance, which means that it can tolerate up to a certain number of Byzantine faults (i.e. malicious or faulty nodes). BFT consensus is often used in permissioned blockchain networks, where the nodes are known and trusted.

11. What is Kafka used for?

Kafka is used as a message bus for Hyperledger Fabric. It is responsible for handling all of the incoming and outgoing messages for the Fabric network.

12. Can you explain what smart contracts are in the context of Hyperledger Fabric?

Smart contracts in Hyperledger Fabric are called chaincode. They are written in Go, Java, or Node.js and are used to define the business logic of a blockchain application. Chaincode is deployed to a peer on a channel and invoked by applications to read and write data to the ledger.

13. Can you give me some examples of when it might make sense to deploy multiple peers per organization as opposed to one peer per organization?

There are a few reasons why you might want to deploy multiple peers per organization as opposed to one peer per organization.

First, if you have a large number of transactions that need to be processed, then multiple peers can help to distribute the load and improve performance.

Second, if you have a large number of organizations participating in the network, then multiple peers can help to improve security by providing more redundancy.

Third, if you have a large number of assets that need to be tracked, then multiple peers can help to improve accuracy by providing more redundancy.

Fourth, if you have a large number of users that need to be able to access the data, then multiple peers can help to improve availability by providing more redundancy.

14. How many organizations can participate in a channel?

A channel can have any number of organizations participate in it.

15. How does membership service provider (MSP) manage identities in Hyperledger Fabric?

The MSP is responsible for managing the identities of the members of a Hyperledger Fabric network. It does this by maintaining a database of identities and providing cryptographic materials to members that they can use to prove their identity. The MSP can also issue certificates that members can use to prove their identity to other members of the network.

16. What are endorsement policies in the context of Hyperledger Fabric?

Endorsement policies are used in Hyperledger Fabric to determine which nodes need to sign off on a transaction before it is considered valid. This is important in ensuring that the network reaches consensus on the state of the ledger.

17. What are the different types of transaction validation policies available in Hyperledger Fabric?

There are four different types of transaction validation policies available in Hyperledger Fabric: Endorsement, Signature, and Hash-based policies. Each type of policy has its own strengths and weaknesses, so it is important to choose the right policy for your particular use case.

Endorsement policies are the most flexible, as they allow for different types of endorsements to be specified. For example, you could require that all transactions be endorsed by a certain number of members of a particular group, or that all transactions be endorsed by a certain percentage of members of a particular group.

Signature policies are less flexible than endorsement policies, but they offer the advantage of being more efficient. With a signature policy, all transactions must be signed by a certain number of members of a particular group.

Hash-based policies are the most restrictive, as they require that all transactions be hashed before they are committed to the ledger. This means that all transactions must be known in advance, which can be a disadvantage in some situations.

18. What are chaincode shims?

Chaincode shims provide an interface between chaincode and the peer node. They handle all of the details of communication between the chaincode and the peer, as well as translating function calls into the appropriate format for the peer.

19. What are the advantages of using Hyperledger Fabric compared to other blockchain solutions like R3 Corda or Ethereum?

Hyperledger Fabric is a permissioned blockchain platform that is well-suited for enterprise use cases. It offers a high degree of flexibility and scalability, and its modular architecture allows for different components to be plugged in or swapped out as needed. Additionally, Fabric uses a unique consensus algorithm called “pluggable consensus” which allows for different consensus mechanisms to be used depending on the use case. This makes Fabric more adaptable than other blockchain solutions.

20. What is your opinion about the security of Hyperledger Fabric?

I believe that Hyperledger Fabric is a very secure platform. It uses a permissioned network which means that only authorized participants can access the network. Additionally, it uses digital signatures and cryptographic hashing to ensure the integrity of data.