A bank has two data centers advertising 10.0.0.0/8 to SD-WAN Controller from different regions. Engineers must ensure branches prefer DC-West for those prefixes without changing TLOC reachability or underlay tunnels. The policy is built in SD-WAN Manager. Which control-policy direction and effect achieves this route preference change?

The correct approach works because OMP route preference is the primary centralized best-path selector propagated by the controller, so an outbound policy applied on the controller toward branches can rewrite only the advertisement seen by branches to favor DC-West for 10.0.0.0/8 while leaving TLOCs, underlay tunnels, and controller topology intact, which is exactly the Manager-built centralized control-policy use case for hub preference without transport changes. The variant that matches DC-East with higher preference is operationally valid for preferring a data center but fails the stated business intent by steering branches to the opposite region, proving that origin-match precision matters more than mechanism correctness. The variant applied outbound toward the data-center sites fails by scope because it only changes the routes the data centers receive, so the branches keep seeing the original preferences and do not favor DC-West. The variant that tags DC-West routes with a community for tracking is common for audit, filtering, or downstream redistribution control, but a community alone does not alter OMP best-path calculation, so branches would still load-share or flap between regions. For exams, remember direction is evaluated from the controller perspective and route preference must be distinguished from TLOC preference, site ID, origin type, and VPN membership, which influence transport or topology rather than prefix selection; always verify in the lab with show sdwan omp routes and show sdwan policy from-vsmart on a branch to confirm the DC-West path shows the higher preference and is installed as best.