Which mechanism changes a router’s forwarding decision without modifying the routing table or altering the IP data plane?

Policy-based routing (PBR) allows network administrators to make forwarding decisions based on criteria other than the destination IP address, such as source IP, application, or protocol. This means the router can forward traffic differently without altering its routing table (which is based on destination IP) or the fundamental IP data plane operations. Nonbroadcast multiaccess (NBMA) describes a network type, not a forwarding mechanism. Packet switching is a general method of data transmission, not a specific mechanism for altering forwarding decisions. The Forwarding Information Base (FIB) is a component of the data plane derived from the routing table; PBR operates independently of the FIB's standard lookup process.