A company wants to use an external appliance between its data center and WAN to optimize email and HTTP communications. The traffic flow must pass this appliance in both directions. The appliance is c

Static routes modify the routing table globally and cannot selectively redirect only specific service traffic like HTTP and email to a single-interface appliance without impacting all other traffic flows.

Adjusting dynamic routing metrics redistributes paths at the routing protocol level and does not provide the per-flow, protocol-selective traffic steering needed to force specific traffic through a single-interface appliance.

NAT modifies source or destination IP addresses for address translation purposes and is not a mechanism designed to transparently insert an optimization appliance into a bidirectional traffic path.

Applying a route map (PBR) on the data center-facing interface intercepts outbound traffic from the data center toward the WAN and redirects it to the appliance IP before it exits, ensuring the appliance processes traffic leaving the data center.

Applying the route map on the appliance-facing interface would create a forwarding loop by redirecting traffic back toward the appliance on the very interface it already arrived from, rather than steering traffic to it from the correct ingress direction.

Applying a route map (PBR) on the WAN-facing interface intercepts inbound traffic arriving from the WAN and redirects it to the appliance IP before it reaches the data center, ensuring the appliance processes return traffic as well.