Refer to the exhibits. The routing tables of FortiGate_A and FortiGate_B and a network topology are shown. Why does FortiGate_B have only one external route available to 100.75.5.1/32? (Choose one answer)

A. rfc-1583-compatible is not set to enable on FortiGate_B.
B. The route to 100.75.5.1/32 shown on FortiGate_B has the lowest cost.
C. FortiGate_A advertises only one external route to FortiGate_B.
D. The subnet 10.0.11.0/24 is not located in the FortiGate_B area

Correct Answer: A

Brave-Dump Clients Votes

A 50%

D 50%

Comments

Shabeeb Kunhipocker 2025-11-27 23:04:08

Selected Answers: A

https://community.fortinet.com/t5/FortiGate/Technical-Tip-OSPFv2-ECMP-for-External-Routes-Expected-Behavior/ta-p/216048

Adam 2026-01-20 10:24:15

Selected Answers: D

In FortiGate A, we can see both 10.0.11.0/24 and 10.0.12.0/24 are directly connected networks, so both above routers in the exhibit can be OSPF neighbors that have connection to 100.75.5.1/32

In FortiGate B, we can see only 10.0.12.0/24 is directly connected network, so only above left router can be OSPF neighbor

ECMP can work with modern RFC 2328.
RFC1583 is just recommended when we have ASBR to depend only on cost, but it doesn't mean ECMP works only with RFC1583, so I think A is wrong.

B is wrong because both routes have same metric 11.

C is wrong because FortiGate A doesn't advertise it, the external network is advertised from ASBRs (both above routers in the exhibit) directly and that advertisement goes to all OSPF routers in all areas as LSA Type 5.

D seems to be the most correct answer to me, so the above right router is just not OSPF neighbor, so it can't be next hop.
What do you think?