You are implementing new addressing with EIGRP routing and must use secondary addresses, which
are missing from the routing table. Which action is the most efficient solution to the problem?
A.
Disable split-horizon on the interfaces with secondary addresses.
B.
Disable split-horizon inside the EIGRP process on the router with the secondary interface
addresses.
C.
Add additional router interfaces and move the secondary addresses to the new interfaces.
D.
Use a different routing protocol and redistribute the routes between EIGRP and the new protocol.
Normally, routers that are connected to broadcast-type IP networks and that use distance-vector
routing protocols employ the split horizon mechanism to reduce the possibility of routing loops.
Split horizon blocks information about routes from being advertised by a router out of any interface
from which that information originated. This behavior usually optimizes communications among multiple routers, particularly when links are broken. However, with nonbroadcast networks,
situations can arise for which this behavior is less than ideal. For these situations, you might want
to disable split horizon with EIGRP and RIP.
If an interface is configured with secondary IP addresses and split horizon is enabled, updates
might not be sourced by every secondary address. One routing update is sourced per network
number unless split horizon is disabled.
Reference. http://www.cisco.com/c/en/us/td/docs/ios/12_2/ip/configuration/guide/fipr_c/1cfrip.html