You set an OSPF router ID but the router still shows a physical-interface IP. What is the least disruptive action to make the configured router ID take effect?

Reloading the OSPF process (e.g., using clear ip ospf process) is the least disruptive way to force OSPF to re-evaluate and apply the newly configured router ID. OSPF elects its router ID only once, during process startup. If a router ID is configured after the OSPF process has already started and elected an ID (often a physical interface IP if no loopback or manual ID was present), the new configuration won't take effect until the process restarts. Specifying a loopback address is a good practice for router ID stability but doesn't immediately change an already elected ID. Rebooting the router is highly disruptive, and saving the configuration alone doesn't restart the OSPF process.