What are three characteristics of the OSPF routing protocol? (Choose three.)

A.
It converges quickly.

B.
OSPF is a classful routing protocol.

C.
It uses cost to determine the best route.

D.
It uses the DUAL algorithm to determine the best route.

E.
OSPF routers send the complete routing table to all directly attached routers.

F.
OSPF routers discover neighbors before exchanging routing information.

Explanation:
Open Shortest Path First
http://docwiki.cisco.com/wiki/Open_Shortest_Path_First

Additional OSPF features include equal-cost, multipath routing, and routing based on upper-layer
type-ofservice
(TOS) requests. TOS-based routing supports those upper-layer protocols that can specify particular
types of service. An application, for example, might specify that certain data is urgent. If OSPF has
high-priority
links at its disposal, these can be used to transport the urgent datagram.
OSPF supports one or more metrics. If only one metric is used, it is considered to be arbitrary, and
TOS is not supported. If more than one metric is used, TOS is optionally supported through the use
of a separate metric (and, therefore, a separate routing table) for each of the eight combinations
created by the three IP TOS bits (the delay, throughput, and reliability bits). For example, if the IP
TOS bits specify low delay, low throughput, and high reliability, OSPF calculates routes to all
destinations based on this TOS designation. IP subnet masks are included with each advertised
destination, enabling variable-length subnet masks. With variable-length subnet masks, an IP
network can be broken into many subnets of various sizes. This provides network administrators
with extra network-configuration flexibility.