Which command disables summarization in a classless routing protocol such as OSPF?

• A. enable auto-summary
• B. auto-summary is turned off by default.
• C. no auto-summary under the routing process
• D. disable auto-summarization per area.

Answer: (C)

In OSPF, automatic summarization occurs at area borders, which can cause subnets to be advertised as broader, classful networks. To stop this behavior, you disable it with the command no auto-summary issued under the OSPF routing process. This turns off automatic summarization, so routes are advertised with their exact subnet prefixes across areas, which helps preserve route specificity in networks that aren’t neatly aligned to classful boundaries. The other options don’t fit because enabling auto-summary would turn the feature back on; claiming it’s off by default is incorrect since auto-summarization is typically enabled by default; and there isn’t a per-area toggle for this feature—the control is a global setting for the OSPF process.