What does a nonzero forwarding address indicate in a type-5 LSA?
A.
It indicates that this link-state ID is eligible for ECMP.
B.
It indicates that this router should have an OSPF neighbor relationship with the forwarding
address before using this link-state ID.
C.
It indicates that the receiving router must check that the next hop is reachable in its routing table
before using this link-state ID.
D.
It indicates that traffic can be directly routed to this next hop in shared segment scenarios where
the external route source is directly connected.
https://www.ietf.org/rfc/rfc2328.txt
Forwarding address
Data traffic for the advertised destination will be forwarded to
this address. If the Forwarding address is set to 0.0.0.0, data
traffic will be forwarded instead to the LSA’s originator (i.e.,
the responsible AS boundary router).