What information does a router running a link-state protocol use to build and maintain its
topological database? (Choose two.)

A.
hello packets

B.
SAP messages sent by other routers

C.
LSAs from other routers

D.
beacons received on point-to-point links

E.
routing tables received from other link-state routers

F.
TTL packets from designated routers

Explanation:
Neighbor discovery is the first step in getting a link state environment up and running. In keeping
with the friendly neighbor terminology, a Hello protocol is used for this step. The protocol will
define a Hello packet format and a procedure for exchanging the packets and processing the
information the packets contain.
After the adjacencies are established, the routers may begin sending out LSAs. As the term
flooding implies, the advertisements are sent to every neighbor. In turn, each received LSA is
copied and forwarded to every neighbor except the one that sent the LSA.