Which design principal improves network resiliency?

Load balancing distributes traffic across available links to improve throughput and utilization, but it does not by itself provide fault tolerance or ensure continued operation when a component fails entirely.

Added redundancy directly improves resiliency by ensuring that if any single component - a link, device, or path - fails, an alternate is immediately available to maintain connectivity. Resiliency is defined as the network's ability to withstand and recover from failures, and redundancy is the primary architectural mechanism that enables this capability.

Confidentiality is a security principle protecting data from unauthorized access and has no relationship to network resiliency or the ability to tolerate component failures.

Reliability is a measurable characteristic describing a component's mean time between failures, not an active design principle that can be added architecturally to improve network-level resiliency.