Virtual Labs

Distributed Consensus - Crash Failures Scenario

What is the primary goal of the distributed consensus algorithm described?

a: To ensure every process runs indefinitely Explanation

Explanation

b: To synchronize clocks across distributed systems Explanation

Explanation

c: To agree on a single value among all non-faulty processes Explanation

Explanation

d: To encrypt communication between processes Explanation

Explanation

How many rounds does the consensus algorithm run to tolerate up to f process failures?

a: f Explanation

Explanation

b: f+1 Explanation

Explanation

c: 2f Explanation

Explanation

d: 2f+1 Explanation

Explanation

What is the fail-stop model in distributed systems?

a: A model where processes fail and then restart automatically Explanation

Explanation

b: A model where processes may crash and stop permanently Explanation

Explanation

c: A model where processes never fail Explanation

Explanation

d: A model where processes send incorrect messages intentionally Explanation

Explanation

What happens in a round if a process does not broadcast its current value?

a: The process is considered non-faulty Explanation

Explanation

b: The process broadcasts a default value Explanation

Explanation

c: No value is received from that process in the round Explanation

Explanation

d: The process restarts the algorithm Explanation

Explanation

What ensures that the consensus value does not change once it is reached?

a: Processes restart after consensus Explanation

Explanation

b: Values are broadcast only once Explanation

Explanation

c: Processes are non-Byzantine and do not alter the agreed value Explanation

Explanation

d: Consensus is achieved before any processes fail Explanation

Explanation

Why is the fail-stop model suitable for this consensus algorithm?

a: It assumes all processes will eventually fail Explanation

Explanation

b: It avoids dealing with adversarial (Byzantine) processes Explanation

Explanation

c: It guarantees synchronization of all processes Explanation

Explanation

d: It requires processes to restart on failure Explanation

Explanation

In the consensus algorithm, what mathematical operation ensures agreement among processes?

a: Taking the maximum of all received values Explanation

Explanation

b: Taking the minimum of all received values including own value Explanation

Explanation

c: Taking the average of all received values Explanation

Explanation

d: Taking the sum of all received values Explanation

Explanation

What is the key insight behind why the algorithm guarantees agreement in f+1 rounds?

a: All processes will have failed by round f+1 Explanation

Explanation

b: At least one round exists where all non-faulty processes can broadcast Explanation

Explanation

c: The minimum value is always known from the first round Explanation

Explanation

d: Byzantine processes are eliminated after f rounds Explanation

Explanation

What condition must be satisfied for the consensus algorithm to guarantee termination and correctness?

a: All processes must start with the same initial value Explanation

Explanation

b: No more than f processes can fail, where f < n Explanation

Explanation

c: Processes must communicate in a specific order Explanation

Explanation

d: The network must be completely connected at all times Explanation

Explanation