Leader election in HLD - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is leader election in distributed systems?

Leader election is the process where nodes in a distributed system choose one node as the coordinator or leader to manage tasks and coordinate actions.

beginner

Why is leader election important in distributed systems?

It ensures coordination, avoids conflicts, and helps manage shared resources by having a single node act as the leader.

intermediate

Name a common algorithm used for leader election.

Bully algorithm and Ring algorithm are common leader election algorithms.

intermediate

What happens if the leader node fails in a distributed system?

A new leader election process starts so that another node becomes the leader to maintain system coordination.

advanced

How does the Bully algorithm select a leader?

Nodes with higher IDs bully lower ID nodes by sending election messages. The highest ID node becomes the leader.

What is the main goal of leader election?

A To increase network traffic

B To delete nodes from the system

C To select one node as coordinator

D To slow down the system

Leader election chooses one node to coordinate tasks and manage the system.

Which algorithm uses node IDs to elect a leader by 'bullying' lower ID nodes?

A Ring algorithm

B Paxos

C Raft

D Bully algorithm

The Bully algorithm elects the highest ID node as leader by sending election messages.

What triggers a new leader election in a distributed system?

A User request

B Leader node failure

C System reboot

D Adding a new node

When the leader node fails, a new election starts to maintain coordination.

Which of these is NOT a property of a good leader election algorithm?

A High latency

B Fault tolerance

C Scalability

D Fairness

High latency is undesirable; good algorithms aim for low latency.

In the Ring algorithm, how is the leader chosen?

A Node with highest ID in a ring passes messages

B Random node selected

C Node with lowest ID in a ring passes messages

D Central server picks leader

In the Ring algorithm, nodes pass election messages in a ring until the highest ID node is selected.

Explain the leader election process and why it is critical in distributed systems.

Think about how nodes agree on one leader and what happens if that leader stops working.

Describe the Bully algorithm steps for electing a leader.

Imagine nodes with numbers competing to be the boss by sending messages.