You instructed your associate to configure Router R2 to reject a redistribution of the 20.0.0.0/8 network, while still receiving routes from other networks connected to Router R1. The diagram below displays the network in place:
When he is finished, you find that the 20.0.0.0/8 network still being advertised and traffic from the 20.0.0.0/8 network is not reaching Router2. You execute the show running-configuration command and see the following output:
What is the problem?
A. The access list was applied to the wrong interface.
B. The access list should have been configured as a distribute list.
C. The access list has an incorrect wildcard mask.
D. The access list is applied in the wrong direction.
Explanation:
The access list should have been created as a distribute list to control route redistribution from the other area. This configuration would prevent the redistribution of the 20.0.0.0/8 network by applying the list as a distribute list under the Border Gateway Protocol (BGP). The proper commands would be:
Router2(config)# router bgp 94688
Router2(config-router)# distribute-list 101 in
To correct the problem with traffic not arriving from the 20.0.0.0/8 network, you must remove the application of the list under interface S0 as well. This would be done by executing the following command set:
Router2(config)# interface Serial1
Router2(config-int)# no ip access-group 101 in
The access list was not applied to the wrong interface. It should not have been applied directly to any interface. When applied directly as an access list to an interface, it will prevent traffic, but not the redistribution of routes.
The access list does not have an incorrect wildcard mask. To prevent the redistribution of a Class C network, the correct wildcard mask is 0.0.0.255.
The access list was not applied in the wrong direction. It should be applied incoming, but should be applied as an incoming distribute list, and it should be applied under the BGP protocol.
Objective:
Layer 3 Technologies
Sub-Objective:
Configure and verify filtering with any protocol