Form groups of 2-4 people and discuss the following exercises.

1. Read book chapter 8.5 about distributed commit (and two-phase commit in
particular).

Summarize the main points the book makes about how the basic idea presented on
the lecture slides needs to be extended to handle different kinds of
failures.

What is the main argument for the book for suggesting three-phase commit should
be needed?

Do the arguments look like the next edition of the book will instead tell us
that actually, we need a four-phase commit? Does this eventually end up as the
problem of Alice and Bob?

2. Identify what the different factors are that make it so hard for Alice and
Bob to agree on their meeting at La Tryste. Can you find a way to remove these
issues?

3. Explain the differences of forward and backward recovery. What is needed for
them? What kinds of situations would make it better to use backward recovery,
and where would forward recovery instead be more optimal?

4. Discuss the basic idea of the Domain Name System (DNS). If you were going to
teach a group of students the main points of DNS as a distributed system, what
would you cover?