Home » Cisco » 400-101 » What might be the cause of the problem?
Refer to the exhibit. R4 is unable to establish an EIGRP adjacency with R3, the only other router on the Fa0/0 LAN segment, although it is able to ping R3. An EIGRP debug on R4 does not provide any clues. What might be the cause of the problem?
A. The passive interface has disabled the transmission of EIGRP multicast hello packets.
B. EIGRP on R4 should be routing to network 209.165.202.128/28.
C. The designated router/backup designated router (DR/BDR) selection requires that at least three routers are on a LAN.
D. The routing metrics on R4 and R3 are different.
Answer: A
Explanation:
The passive-interface command disables the transmission and receipt of EIGRP hello packets on an interface. Unlike IGRP or RIP, EIGRP sends hello packets in order to form and sustain neighbor adjacencies. Without a neighbor adjacency, EIGRP cannot exchange routes with a neighbor. Therefore, the passive-interface command prevents the exchange of routes on the interface. Although EIGRP does not send or receive routing updates on an interface configured with the passive-interface command, it still includes the address of the interface in routing updates sent out of other non-passive interfaces.
