最新 [2024年06月01日]Linux Foundation HFCP試験練習でテストの素晴らしい結果を出そう
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質問 # 24
Which are the transaction steps that are managed by the Fabric gateway service?
- A. Realizing a distributed verifiable random function for leader election.
- B. Finding a nonce for a pre-image of a hash function for mining.
- C. Collect transactions into a block and eliminating invalid transactions.
- D. Evaluate, endorse, submit, and get commit status.
正解：D
解説：
The transaction steps managed by the Fabric gateway service in Hyperledger Fabric are to evaluate, endorse, submit, and obtain the commit status of transactions. This service simplifies the process for clients by handling these critical transaction steps, which facilitates more efficient transaction processing and management within the network .
質問 # 25
What is the advantage of using state-based endorsement policy over a chaincode or collection level endorsement policy?
- A. It can be used without complex configuration transactions, only a JSON configuration file is needed.
- B. It provides a way to set endorsement policy on a global Hyperledger Fabric farm level with one configuration
- C. It provides fine-tuned endorsement policy on key level, update is possible without chaincode update
- D. It provides a way to set endorsement policy for multiply keys with one chaincode configuration update.
正解：C
解説：
State-based endorsement policies in Hyperledger Fabric offer a significant advantage by allowing endorsement policies to be specified at the level of individual state keys within the ledger. This granularity means that the endorsement policy for specific assets or data points can be tailored independently of others and can be updated without the need to redeploy or update the chaincode itself. This flexibility supports dynamic business needs and complex governance structures where different assets may require different endorsement levels based on their sensitivity or value .
質問 # 26
Which channel feature allows organizations to run different versions of Hyperledger Fabric on their peer nodes?
- A. Endorsement policies
- B. Anchor peers
- C. Consensus protocols
- D. Channel capabilities
正解：D
解説：
Hyperledger Fabric allows different versions of the platform to coexist and interoperate on the same network through the use of channel capabilities. Channel capabilities enable organizations running different versions of Fabric binaries to participate on the same channel. These capabilities govern the features that are used by peer nodes and set the minimum version of the Fabric binaries that can be run by peers joined to the channel. This allows for heterogeneousnetwork environments where different nodes might be running different versions of Fabric software .
質問 # 27
Each peer in the Hyperledger Fabric network hosts a copy of the ledger, which also belongs to what component?
- A. The Ordering node
- B. The NoSQL databases
- C. The membership services
- D. A member channel
正解：D
解説：
In Hyperledger Fabric, each peer in the network hosts a copy of the ledger, which is associated with a member channel. The ledger itself is comprised of a blockchain to store the immutable, sequenced record in blocks, and a state database to maintain the current state of the ledger. There is one ledger per channel, and each peer maintains a copy of the ledger for each channel of which they are a member .
質問 # 28
The Gateway service manages which of the following activities on behalf of the client application?
- A. Transaction submission
- B. User enrollment and authentication
- C. Chaincode
- D. Channel management
正解：A
解説：
In Hyperledger Fabric, the Gateway service manages the transaction submission process on behalf of the client application. This service simplifies the interaction with the network by abstracting the details of transaction construction, endorsement, and submission. The Gateway service assembles the necessary endorsements according to the relevant chaincode endorsement policies and submits the transaction to the ordering service.
This role of the Gateway enhances the usability and efficiency of transaction processing, reducing the complexity for client applications by handling these critical steps internally.
質問 # 29
What should be taken into account at implementing efficient CouchDB queries from chaincode?
- A. Using OLAP (Online analytical processing) and Cube functionality of CouchDB is enough to implement efficient queries.
- B. Using advanced relational algebra and SQL query language options of CouchDB is enough to implement efficient queries.
- C. Using indexes, focusing on simple queries and avoiding full index scans like with operators $or, $in and
$regex. - D. Using complex indexes for certain columns is enough even if full scan operators like $or, $in and $regex are used.
正解：C
解説：
When implementing efficient CouchDB queries from chaincode in Hyperledger Fabric, it is important to use indexes effectively and focus on crafting simple queries that avoid full index scans. Operators such as $or, $in, and $regex can lead to performance issues because they often result in full scans of the database or index.
Instead, it is recommended to structure queries that make optimal use of indexes, targeting specific key-value pairs or ranges to minimize the amount of data scanned during query execution. This approach helps in maintaining high query performance and reducing the load on the CouchDB database, which is crucial for achieving efficient data retrieval in a blockchain environment.
質問 # 30
In a production environment, what peer items require on-going monitoring?
- A. Only the chaincode containers since they handle the business logic.
- B. All peer containers, including their CPU, network, and memory.
- C. Only the orderer service since it manages the ordering of transactions.
- D. Onlythe peer nodes that are runningchaincode, since they consume most resources.
正解：B
解説：
In a production environment of Hyperledger Fabric, it is essential to monitor all peer containers comprehensively, including their CPU, network, and memory usage. This is because each peer node plays a critical role in maintaining the network's overall health and efficiency. Monitoring these resources helps in detecting potential bottlenecks or failures early, ensuring the smooth operation of the blockchain network.
Focusing only on specific components like the orderer service or chaincode containers would provide a limited view of the network's health and could lead to issues being overlooked. Comprehensive monitoring enables administrators to maintain optimal performance and reliability across the entire network.
質問 # 31
When deploying an Orderer environment, variables must be customized or overridden in which artifact?
- A. docker-compose.yaml
- B. orderer.yaml
- C. configtx.yaml
- D. crypto-config.yaml
正解：B
解説：
When deploying an Orderer environment in Hyperledger Fabric, the primary configuration file that must be customized or overridden isorderer.yaml. This file contains the configuration settings specifically for the orderer node, including general ledger type, consensus type, and various operational settings like batching, timeouts, and MSP configurations. Other files likecrypto-config.yaml,docker-compose.yaml, and configtx.yamlserve different roles.crypto-config.yamlis used for generating cryptographic material, docker-compose.yamlfor defining services, networks, and volumes for containers, andconfigtx.yamlfor channel configuration and consortium definitions. Therefore,orderer.yamlis critical for setting up the orderer's behavior and parameters in the network environment.
質問 # 32
What types of events committed to the ledger can client applications receive using the peer's event service?
- A. Only block events
- B. Both chaincode and block events
- C. Only chaincode events
- D. Neither chaincode nor block events
正解：B
解説：
In Hyperledger Fabric, client applications can subscribe to receive both chaincode events and block events using the peer's event service. Chaincode events are generated by the chaincode itself, typically based on specific conditions coded within the chaincode operations, and are used to notify applications of specific state changes or significant occurrences. Block events inform about the addition of new blocks to the ledger, which may contain multiple transactions. This dual capability allows client applications to effectively monitor transaction confirmations and specific chaincode outputs in real time, which is critical for applications that rely on up-to-date blockchain data for processing decisions.
質問 # 33
Which pluggable component in the Hyperledger Fabric modular architecture is responsible for identities?
- A. Peer Node
- B. Membership Service Provider
- C. Endorsement Policy
- D. Ordering Service
正解：B
解説：
In Hyperledger Fabric's modular architecture, the Membership Service Provider (MSP) is the pluggable component responsible for handling identities. The MSP abstracts the identity validation and authentication processes, allowing organizations to implement their preferred identity services while maintaining interoperability within the network. It defines the rules by which identities are validated, issued, and revoked.
This component is essential for the permissioned nature of Hyperledger Fabric, ensuring that only authorized participants can execute specific actions on the network.
質問 # 34
What is a range query with a start and end key?
- A. A query that searches for a specific value in a composite key and all values after it.
- B. A query that searches for all the key field in the value.
- C. A query that searches for all keys that are in the range defined by the start and end keys.
- D. A query that searches for ledger entries that have values matching the range.
正解：C
解説：
In Hyperledger Fabric, a range query with a start and end key is a type of query that searches for all ledger entries whose keys fall within the specified range defined by the startKey and endKey. This is used, for example, to retrieve a subset of assets from the ledger based on their key values, effectively iterating over a specified range .
質問 # 35
What gRPC status code might you expect to be associated with an error invoking a transaction as a result of a transient failure, such as a network disconnection between the client application and Gateway peer?
- A. DEADLINE EXCEEDED
- B. ABORTED
- C. UNAVAILABLE
- D. FAILED PRECONDITION
正解：C
解説：
The gRPC status code "UNAVAILABLE" is commonly expected in scenarios involving transient failures in network communication, such as a disconnection between the client application and the Gateway peer. This status code indicates that the service is currently unavailable, often due to network issues or service downtime, making it suitable for situations where the failure is temporary and the request can be retried. This differs from other codes like "ABORTED" or "DEADLINE EXCEEDED," which represent different types of errors related to the transaction logic or timing issues, respectively. "FAILED PRECONDITION" would be inappropriate for network disconnections as it suggests issues with the request's preconditions, not the network status.
質問 # 36
Which of the following is the identity solution in Hyperledger Fabric?
- A. Hyperledger Fabric CA
- B. Hyperledger Fabric Orderer
- C. Hyperledger Fabric SDK
- D. Membership Service Providers
正解：D
解説：
In Hyperledger Fabric, the identity solution that manages user identities and authenticates participants on the network is facilitated by Membership Service Providers (MSPs). MSPs are crucial for defining the rules by which identities are validated, authenticated, and allowed access to the network. MSPs handle the issuance of certificates and define the roles and permissions associated with participant identities, enabling permissioned interactions on the blockchain. This differs from Hyperledger Fabric CA, which primarily issues and revokes certificates as part of identity management but is used in conjunction with MSPs to provide comprehensive identity solutions within the network.
質問 # 37
When using "off-line signing" in the Fabric Gateway client API, what information from each message is used to generate the cryptographic signature?
- A. The message digest
- B. The transaction ID
- C. The transaction validation code
- D. The client X.509 certificate
正解：A
解説：
When using "off-line signing" in the Fabric Gateway client API, the cryptographic signature is generated using the message digest. This digest is a hashed representation of the transaction's content, ensuring the integrity and non-repudiation of the transaction as it moves through the Fabric network. This method allows for secure transaction signing without exposing private keys directly on the client-side, aligning with security best practices .
質問 # 38
When building a test network, how many nodes are adequate for an Ordering Service?
- A. There is no set number of nodes required for an Ordering Service.
- B. Three ordering nodes are needed for a test Ordering Service.
- C. One ordering nodes is sufficient for an Ordering Service.
- D. Ordering Service nodes are optional in a test network.
正解：C
解説：
For a test network in Hyperledger Fabric, one ordering node is sufficient to form an Ordering Service7. The test network typically uses a single-node Raft ordering service for simplicity and educational purposes. However, for production networks, a multi-node ordering service is recommended for fault tolerance and high availability8.
質問 # 39
What is the purpose of the ordering service in Hyperledger Fabric model?
- A. To manage the identities of the participants in the network
- B. To validate transactions and maintain the blockchain ledqer
- C. To assemble transactions into blocks for the blockchain ledqer.
- D. To endorse transactions and update the world state.
正解：C
解説：
The primary purpose of the ordering service in Hyperledger Fabric is to assemble transactions into blocks and ensure their correct sequencing on the blockchain ledger. This service takes validated transactions, orders them chronologically, and packages them into blocks. These blocks are then distributed to all peers on the network for final validation and commitment to their respective ledgers. This process is crucial for maintaining the integrity and consistency of the ledger across the distributed network. The ordering service does not manage identities or endorse transactions, nor does it validate transactions or directly maintain the blockchain ledger beyond the sequencing and packaging of transactions.
質問 # 40
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