Discuss whether message passing or DSM is preferable for fault-tolerant applications.

What will be an ideal response?

Consider two processes executing at failure-independent computers. In a message passing system, if one process has a bug that leads it to send spurious messages, the other may protect itself to a certain extent by validating the messages it receives. If a process fails part-way through a multi-message operation, then transactional techniques can be used to ensure that data are left in a consistent state.
Now consider that the processes share memory, whether it is physically shared memory or page-based DSM. Then one of them may adversely affect the other if it fails, because now one process may update a shared variable without the knowledge of the other. For example, it could incorrectly update shared variables due to a bug. It could fail after starting but not completing an update to several variables.