In OSPF, what type of route metric is used and what is the role of areas, especially area 0?

• A. OSPF uses hop count as metric; Areas are not hierarchical.
• B. OSPF uses cost as its metric; Areas segment the network with Area 0 as the backbone.
• C. OSPF uses distance vector metrics; Area 0 is optional.
• D. OSPF uses bandwidth as metric; Areas are used only for summary routes.

Answer: (B)