Network Design & Administration Flashcards

A Raft ordering service has 5 orderer nodes. How many nodes can fail while the channel still orders transactions?

Answer: 2

Raft needs a quorum of floor(n/2)+1 = 3 nodes, so 2 of 5 can fail.

In Fabric 2.3 and later, which tool lets an admin create a channel on orderers without a system channel?

Answer: The channel participation API (osnadmin)

The osnadmin CLI uses the orderer's channel participation API to join orderers to application channels.

What is the main purpose of an anchor peer?

Answer: To enable gossip communication and discovery across organizations

Anchor peers let peers of different organizations discover each other via gossip.

Which fault tolerance model does the Raft ordering service provide?

Answer: Crash fault tolerance

Raft is crash fault tolerant; it does not protect against malicious orderers.

What does a channel's genesis (config) block contain?

Answer: Channel configuration including MSP definitions, policies and orderer settings

The config block defines the channel's members, policies, capabilities and ordering parameters.

To add a new organization to an existing channel, what must happen by default?

Answer: A config update transaction is signed by enough admins to satisfy the modification policy

Adding an org changes channel config, which requires signatures meeting the relevant modification policy (default majority of admins).

Which orderer parameter forces a block to be cut after a set time even if it is not full?

Answer: BatchTimeout

BatchTimeout is the wait time before a batch is cut into a block.