Useful Links

Notes

Past Exams

SE1 Exam WS 2014/15

Performance

• Give 3 reasons why sequential access to RAM is faster than random.
• Suggestion on the underlying data structure.
• How does checksum mismatch happen? How to detect it?

Idempotent

• Define idempotent request.
• Which of the following is idempotent?
• HTTP PUT
• AppendEntries RPC
• RequestVotes RPC
• acquire lock

CAP theorem

• What's acronym for CAP? And what is the statement?
• Based on the assumption that we cannot sacrifice one of the properties, illustrate the impossible situation.

Raft

• Define primary/backup state replication.
• Define atomic broadcast, and compare to consensus.
• What kind of order does Raft guarantee?
• Why is atomic broadcast needed in primary/backup?
• Name 3 safety properties that Raft guaranteed.

SE1 Exam WS 2015/16

• What is stateless protocol?
  • Advantages and disadvantages.
  • Hard state, Soft state, session state. What are these and how will they behave in terms of lifetime/availability.
• Describe in your own words what is FEC and how it solves error?
• Primary/backup. atomic broadcast.
• Lamport
  • Vector, compare to lamport
  • Name + and - from both.
• Raft
  • Split Votes in Raft.