Why should networks advertise only ROA-covered prefixes to peers?

• A. ROA filters out all traffic.
• B. ROA causes routing instability.
• C. To ensure that ROA-based validation can pass and to reduce acceptance of invalid routes.
• D. ROA is optional for all routes.

Answer: (C)

ROA-based validation uses Route Origin Authorizations to cryptographically authorize which origin AS is allowed to announce a prefix and up to what length. When peers enable this validation, they will accept a route only if it is covered by a valid ROA. By advertising only ROA-covered prefixes, you ensure that remote validators can pass the route’s origin checks, and you minimize the chance that legitimate routes are blocked while also reducing the exposure to invalid or hijacked routes. In short, it strengthens trust in the routing path by aligning announcements with what ROAs authorize, improving both security and stability.