For example, in the earlier summarization example, subnets 10.3.4.0/24, 10.3.5.0/24, 10.3.6.0/24,
and 10.3.7.0/24 together define a range of addresses from 10.3.4.0 to 10.3.7.255. The summary
route in Example 21-1 (10.3.0.0/16) works. However, it includes a lot of IP addresses that are not in
those four original subnets, because it includes the range from 10.3.0.0 to 10.3.255.255. As it turns
out, a different option for this summary route—10.3.4.0/22—has a range of addresses that exactly
matches the range for these four subnets (10.3.4.0–10.3.7.255). By the definition listed here, both
10.3.0.0/16 and 10.3.4.0/22 work, but 10.3.40/22 is the best summary route