Exam 300-420 topic 1 question 25 discussion

Passive Interface: When an interface is configured as a passive interface in EIGRP, it stops sending and receiving EIGRP hello packets. This means that the router will not form EIGRP neighbor relationships on that interface. Effect on Routing Updates: The effect of the passive interface command in EIGRP is that it suppresses both outgoing and incoming routing updates. This is because EIGRP forms neighbor relationships by exchanging hello packets, and these relationships are required for the exchange of routing updates. Use Cases: The passive interface feature is typically used in scenarios where you want to prevent EIGRP from sending or receiving updates on an interface, but still want the network connected to that interface to be advertised to other EIGRP neighbors.

Making it a stub network (Option D) will not disable Hellos being sent through any interface. Instead, option B is suggesting to use Network command + passive interface command (Notice it does not say passive-interface default) so, in this case, the engineer should use his/her own criteria to determine on which interface to apply this command to. That is my justification to say that option B is correct.

I am choosing B. The answer is in the question. Advertise the local LAN: via network command, however, without sending unnecessary multicast messages. so we make it passive.

The answer for this one is 100% B. When you configure an interface as Passive EIGRP will not form a neighbor adjacency with any other routers on the interface, there for it will not send Multicast Messages on Passive Interfaces, in this case we want to configure our Passive Interface on the Local LAN.

D is correct

B. Advertise the local LAN using the network command and the passive-interface feature The engineer should use the network command to advertise the local LAN network in EIGRP and then apply the passive-interface feature to the LAN interface. By doing this, the router will advertise the local LAN network to remote EIGRP neighbors, but it will not send any unnecessary EIGRP multicast messages on the local LAN. The passive-interface feature prevents EIGRP from sending updates or forming adjacencies on the specified interface, which is useful in this scenario since there is only one Layer 3 router at the site.

b is correct. if you make it a stub then it wont advertise the local lan to the remote neighbor, which is a requirement. the router has as atleast 2 interfaces. one that connects to the remote neighbor and one for the local lan. passive interface can be configured per interface. so you make the local lan interface a passive interface done!

I think the confusion on this question is that the passive interface would be to the LAN and not to the remote router otherwise they cant form an adjacency, question states they dont want to send unnecessary multicast traffic to the LAN (not remote router). Answer is B

B is correct. imagine there is 2 interfaces on the router, one connect to the WAN and the other connect to the LAN, in the router EIGRP, both interface must advertise by netowrk command, and the mulitcast of hello message started at this point. As the question state only 1 router on the network, there is no peer on LAN and passive-interface will stop the multicast for peering. and of cause, stub will eliminate query (send as multicast) from hub site via WAN, while the question is asking about LAN, so B is correct.

Basically TMe392 is right. Passive interface will bring down the adjacency! B is not correct! D is the correct option

Sorry, forget my last comment, the correct answer is definitely B as the requirement is simply to advertise the network but NOT send MC traffic on the local LAN. For this you have to make it a passive interface. There are no requirements stated to make it a stub.

Agree with D

D is right as passive-interface block incoming and outgoing eigrp route updates

Provided answer is correct