Router R1 exists in an Enterprise that uses EIGRP as its routing protocol. The show ip route
command output on router R1 lists the following phrase: “Gateway of last resort is 1.1.1.1 to
network 2.0.0.0”. Which of the following is most likely to have caused this output to occur on
R1?

A.
R1 has been configured with an ip default-network 2.0.0.0 command.

B.
R1 has been configured with an ip route 0.0.0.0 0.0.0.0 1.1.1.1 command.

C.
R1 has been configured with an ip route 2.0.0.0 255.0.0.0 1.1.1.1 command.

D.
Another router has been configured with an ip default-network 2.0.0.0 command.

E.
Another router has been configured with an ip route 2.0.0.0 255.0.0.0 1.1.1.1 command.

Explanation:
The phrase quoted in the question means that R1 is using its route for class A network
2.0.0.0 to decide where to send packets by default. R1’s route for network 2.0.0.0 must have
1.1.1.1 as its next-hop router. This phrase occurs when EIGRP has learned a route for class
A network 2.0.0.0 that has been flagged as a candidate default route by another router. The
router flagging a route as a candidate default route, using the ip default-network command,
does not actually use the route as its default route.