Which route filtering solution must the engineer employ?

An engineer must peer with an ISP for internet connectivity using BGP, initially, the engineer wants to receive only specific prefixes from the ISP and a default route. However, the solution must provide the flexibility to add prefixes in the future at short notice. The ISP has a two-week change process in place.

Which route filtering solution must the engineer employ?
A . Request a limited internet routing table and a default route from the ISP and configure
the BGP max-limit to 1 with an access list that permits only the specific internet prefixes and blocked networks
B. Request only the required prefixes and default route be advertised from the ISO with whitelisted networks
C. Request a full internet routing table and a default route from the ISP and configure inbound route filtering with a prefix list that permits the default route and required prefixes
D. Configure outbound route filtering on the enterprise and ISP so that the enterprise tell the ISP which prefixes are required

View Answer

Answer: C

Explanation:

any change on the prefix list, engineer only need to update the preifx list and restart the BGP peer to the ISP. soft-reconfiguration inbound could be used to reduce down time of reset BGP peer, but it require lots of memory and in this case, connection to ISP and tons of route learnt will not be apporitated.