Question

A network engineer redistributes several OSPF learned subnets (172.16.4.0/24, 172.16.5.0/24, 172.16.6.0/24, 172.16.7.0/24) into RIP on a border router. To reduce the RIP table size on downstream routers, the engineer applies the interface command 'ip summary-address rip 172.16.4.0 255.255.252.0' on the RIP-facing interface, but downstream routers still receive all four individual /24 routes instead of the single summary. What is the most likely cause?

Accepted Answer

RIPv1 is running, which does not carry subnet mask information and cannot advertise the /22 summary

Answer

RIP manual summarization requires all component routes to be present in the routing table before the summary is generated, and one component is missing

Answer

RIPv2 auto-summary is enabled, which overrides the interface-level summary-address and re-advertises the classful components

Answer

The summary mask 255.255.252.0 is invalid for RIP because manual summaries must fall on a classful (/16) boundary