A、 Filtering is only useful when combined with route summarization

B、 It is best to filter （allow） the default and summary prefixes only in the Enterprise Edge to remotesites or site-to-site IPsec VPN networks

C、 IGPs （for example EIGRP or OSPF） are superior to route filtering in avoiding in inappropriatetransit traffic through remote nodes or inaccurate or inappropriate routing updates

D、 The primary limitation of router filtering is that it can only be applied on outbound updates