A network engineer deployed a redundant switch stack to increase system availability. However, the budget can only cover the cost of one ISP connection. Which of the following best describes the potential risk factor?

The correct answer is that there is a single point of failure. While the switch stack provides redundancy for the internal network, the single ISP connection remains a critical dependency. If this connection fails, the entire network loses internet access, regardless of the redundant switches. This creates a single point of failure that undermines the overall availability goal. The other options are less accurate: The equipment MTBF (Mean Time Between Failures) being unknown is a general risk but not the best description of the specific risk introduced by the single ISP connection. The ISP having no SLA (Service Level Agreement) is a contractual risk, but the physical single point of failure of the connection itself is the more direct technical risk to availability. An RPO (Recovery Point Objective) not being determined relates to data loss tolerance, not directly to the availability of the network connection itself.