In order to achieve the utmost fault tolerance, as a network administrator, you want to ensure that critical devices are all equipped with redundant NICs, routers, and processors, which are able to immediately assume the duties of an identical component in case one of the components fails. Which of the following will help you ensure these devices contain the necessary components you require?
a. Hot-swappable parts
b. Load balancing
c. Automatic failover
d. Clustering