Which option is a fate-sharing characteristic in regards to network design?

Fate-sharing describes the condition where multiple services or components share the same failure domain - meaning if the single shared element fails, every service depending on it fails simultaneously. It is used in network design discussions to highlight the risk of insufficient redundancy or improper separation of failure domains.

Protecting the network against distribution-layer failures describes a redundancy or high-availability design goal, which is the opposite intent of fate-sharing.

Acting as a stateful forwarding device describes a firewall or session-aware network function, unrelated to fate-sharing.

Data sequencing and acknowledgment mechanisms describe TCP transport-layer behavior, not a network design fate-sharing characteristic.