What are two network-based fault tolerance techniques?

NIC teaming (also called link aggregation or bonding) combines multiple physical network interface cards on a single server into one logical interface, so that if one physical NIC or its associated cable/port fails, traffic automatically continues flowing over the remaining active NIC(s) without interrupting connectivity, while often also providing increased aggregate bandwidth. Switch aggregation similarly combines multiple physical links between switches, or provides redundant switch paths, so that the failure of a single link or switch does not sever network connectivity between devices. Both techniques directly provide redundancy at the network hardware and link layer, making them correctly classified as network-based fault tolerance techniques that keep connectivity alive despite the failure of an individual physical component. Multipathing (A) is typically a storage-network technique for maintaining multiple I/O paths between a host and storage array, and while network-related, 'NIC isolation' is not a standard recognized fault tolerance mechanism. Traffic shaping (B) is a quality-of-service technique for controlling bandwidth usage and prioritization, not a redundancy or failure-tolerance mechanism. VLAN configuration (B, C) segments and organizes network traffic logically for security and management purposes, but does not by itself provide failure redundancy. NIC teaming and switch aggregation are the correct pairing.

Reference topic: Fault Tolerance Techniques - Network-Based Redundancy (NIC Teaming, Switch Aggregation).