Which partial routing table entry in the Central router represents a route summary that represents the LANs in Phoenix but no additional subnets?

Refer to the exhibit.

The Lakeside Company has the internetwork in the exhibit. The administrator would like to reduce the size of the routing table on the Central router.

Which partial routing table entry in the Central router represents a route summary that represents the LANs in Phoenix but no additional subnets?
A . 10.0.0.0/22 is subnetted, 1 subnets
D 10.0.0.0 [90/20514560] via 10.2.0.2, 6w0d, Serial0/1
B . 10.0.0.0/28 is subnetted, 1 subnets
D 10.2.0.0 [90/20514560] via 10.2.0.2, 6w0d, Serial0/1
C . 10.0.0.0/30 is subnetted, 1 subnets
D 10.2.2.0 [90/20514560] via 10.2.0.2, 6w0d, Serial0/1
D . 10.0.0.0/22 is subnetted, 1 subnets
D 10.4.0.0 [90/20514560] via 10.2.0.2, 6w0d, Serial0/1
E . 10.0.0.0/28 is subnetted, 1 subnets
D 10.4.4.0 [90/20514560] via 10.2.0.2, 6w0d, Serial0/1
F . 10.0.0.0/30 is subnetted, 1 subnets
D 10.4.4.4 [90/20514560] via 10.2.0.2, 6w0d, Serial0/1

View Answer

Answer: D

Explanation:

All the above networks can be summarized to 10.0.0.0 network but the question requires to “represent the LANs in Phoenix but no additional subnets” so we must summarized to 10.4.0.0 network. The Phoenix router has 4 subnets so we need to “move left” 2 bits of “/24″-> /22 is the best choice – D is correct.