Assessment 2

Students must receive a score of 7/8 to proceed. All questions are multiple choice questions and there could be one or more possible correct answers.

1. What may happen if a node does not notify other nodes about a transaction?

   1. Another transaction may spend the same coins and the node’s block may be rejected. ✓

   2. Other nodes are completely unable to verify the block containing that transaction once it is propagated to the network.

   3. Blocks generated by the node containing it may be rejected as a double spend. ✓

   4. All of the above.

2. Why does a node need to be able to receive a block as quickly as possible?

   1. For its own verification.

   2. Since energy that is spent building upon a superseded block is wasted.

   3. To keep its own blocks from potentially being invalid.

   4. All of the above. ✓

3. Nodes need to make sure that other nodes on the network become aware of their _______ in order to have the best chance of _______ as part of the _______.

   1. presence on the network, forming dense connections, Small World Network

   2. block proposals, being validated, blockchain '

   3. noticed transactions, nodes connecting to it, small world network

   4. block immediately, it being built upon, longest proof of work chain ✓

4. Transaction inputs using particular ______ can be sorted into specific optimized pipelines. Once the inputs have been validated, _______and _______ to the block template.

   1. scriptSig, the transactions is reassembled, its hash added

   2. Template types, the transaction is valid, appended ✓

   3. Outputs, the inputs, outputs are added

   4. Templates, the templates are reassembled, added

5. What can payment channels allow for?

   1. Cumulative small payments.

   2. Periodic settlement based on usage instead of subscription.

   3. Paying only for what you consume of a service or product.

   4. All of the above ✓

6. What is a node’s primary function?

   1. A blockchain network monitoring service.

   2. A backbone for financial services providers.

   3. A transaction validator and timestamper. ✓

   4. All of the above.

7. What are blocks?

   1. The output of the network’s transaction validation engines.

   2. Timestamped records of transactions. ✓

   3. The first line of defense against double spends.

   4. All of the above.

8. Bitcoin's economics are finely tuned and ______ can negatively impact network performance. For this reason Bitcoin must be built and operated as ______ with work instead focused on building _______.

   1. dishonest behavior, transparently as possible, trust and simplicity

   2. large scale utilization, settlement layer, alternative methods of scaling Bitcoin

   3. minor protocol changes, infrastructure, advanced node client technologies ✓

   4. improper usage, a security protocol, methods to prevent attacks on the network