Route summarization can effectively reduce the number of BGP routes.

Option B is false . By default, when the aggregate command is used without any options , BGP generates a summary route , and suppresses the specific routes that fall under that summary. To advertise both specific and summary routes, you must explicitly configure the detail-suppressed option to control whether specifics are suppressed or not.

Explanation of the other options:

A is correct: When suppress-policy is specified, only specific routes matching the policy are advertised; others are suppressed.

C is correct: The summary automatic command causes summarization based on classful boundaries, which is a legacy behavior.

D is correct: With detail-suppressed, only the summary route is advertised, not specific prefixes.

Reference from Huawei HCIP-Datacom-Core Technology Study Guide:

“The aggregate command suppresses specific routes by default unless explicitly configured otherwise. Use of suppress-policy or detail-suppressed allows control over which routes are advertised.”

(Chapter: BGP Advanced Features – Section: Route Aggregation)