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
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 summarize 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.
Route summarization (also called route aggregation or supernetting) can reduce the number of routes that a router must maintain, because it is a method of representing a series of network numbers in a single summary address.
4 is the Difference between /24 and /22.
2^2 = 4
Phoenix has 4 subnets
4.0.0 not 4.4.0