My Note (RIP)

RIP

Validate-update-source:

RIP and IGRP are the ONLY TWO routing protocols that validate the source IP address of incoming updates. Before RIP and IGRP routing protocols accept routes from a given neighbor, they want to make sure that the source IP address of the advertising router is form the same IP address space as the link that the two routers are connected to. If the routers that have to exchange routing information are from different IP address spaces, then the source validation should be negated using "no validate-update-source"

NOTE: even though the network are in the routing table, they are NOT reachable because it does not have NLRI. Static route to next hop ip address (the other interface ip address) via directly connect interface will be needed to provide reachability.
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Exchange update:

If the "passive-interface" command is NOT used, the routers will send both Unicast and Multicast updates to each other when using with neighbor command.

If the "passive-interface" command is used, the routers will send Unicast updates to each other when using with neighbor command.

If the "ip rip v2-broadcast" command is used under interface, routing exchange will be using with broadcast.