Hi Christina I,
Executing the passive-interface command from within the router OSPF configuration mode, specifically at the (config-router)# prompt, is the exact necessary step. This action stops the device from transmitting OSPF Hello packets to the local area network over the 224.0.0.5 multicast address, securing the routing topology from unauthorized peerings while conserving bandwidth.
Furthermore, the assessment of the router IDs and VLAN states is fully correct. Because no manual Router ID or virtual Loopback interface was established, the OSPF process accurately defaulted to electing the highest active physical IP address to form neighbor adjacencies. Finally, default VLAN Switched Virtual Interfaces lacking an assigned IP address remain in an administratively down state, which is standard behavior and irrelevant to the OSPF routing completion score.
I hope this answer has provided useful information. If it did, please click on "accept answer". If you have questions, feel free to leave a comment.
VPHAN