What set of commands will properly configure the Core router?

Refer to the exhibit.

The network associate is configuring OSPF on the Core router. All the connections to the
branches should be participating in OSPF. The link to the ISP should NOT participate in OSPF
and should only be advertised as the default route. What set of commands will properly configure
the Core router?

A.
Core(config-router)# default-information originate
Core(config-router)# network 10.0.0.0 0.255.255.255 area 0
Core(config-router)# exit
Core(config)# ip route 0.0.0.0 0.0.0.0 10.10.2.14

B.
Core(config-router)# default-information originate
Core(config-router)# network 10.10.2.13 0.0.0.242 area 0
Core(config-router)# exit
Core(config)# ip route 0.0.0.0 0.0.0.0 10.10.2.14

C.
Core(config-router)# default-information originate
Core(config-router)# network 10.10.2.16 0.0.0.15 area 0
Core(config-router)# exit
Core(config)# ip route 0.0.0.0 0.0.0.0 10.10.2.14

D.
Core(config-router)# default-information originate
Core(config-router)# network 10.10.2.32 0.0.0.31 area 0
Core(config-router)# exit
Core(config)# ip route 0.0.0.0 0.0.0.0 10.10.2.14

Explanation:
There are two ways to inject a default route into a normal area.1. If the ASBR
already has the default route in its routing table, you can advertise theexisting 0.0.0.0/0 into the
OSPF domain with the default-information originate router configuration command.2. If the ASBR
doesn’t have a default route, you can add the keyword always to the default-information originate
command (default-information originate always).This command will advertise a default route into
the OSPF domain, regardless of whether it has a route to 0.0.0.0. Another benefit of adding
always keyword is that it can add stability to the internetwork. For example, if the ASBR is learning
a default route from another routing domain such as RIP and this route is flapping, then without
the always keyword, each time the route flaps, the ASBR will send a new Type 5 LSA into the

OSPF domain causing some instability inside the OSPF domain. With the always keyword, the
ASBR will advertise the default inside the OSPF domain always, In the example shown here, only
choice C is correct as the wildcard mask correctly specifies the 10.10.2.16 0.0.0.15 networks,
which include all IP addresses in the 10.10.2.16-10.10.2.31 range. In this question we were told
that the ISP link should NOT be configured for OSPF, making choice A incorrect.
http://www.cisco.com/en/US/tech/tk365/technologies_configuration_example09186a00801ec9f0.s
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