longest match rule ??

[user29808]

router# show ip route
....
172.30.0.0/16 is variably subnetted, 2 subnets, 2 masks
D 172.30.32.0/20 [90/4879540] via 10.1.1.2
D 172.30.32.0/24 [90/25789217] via 10.1.1.1
S* 0.0.0.0/0 [1/0] via 10.1.1.3

Remembering that the 172.30.32.0/24 network includes the addresses 172.30.32.0 through 172.30.32.255, and the 172.30.32.0/20 network includes the addresses 172.30.32.0 through 172.30.47.255, we can then try switching three packets through this routing table and see what the results are.

• A packet destined to 172.30.32.1 is forwarded to 10.1.1.1, since this is the longest prefix match.
  
• A packet destined to 172.30.33.1 is forwarded to 10.1.1.2, since this is the longest prefix match.
  
• A packet destined to 192.168.10.1 is forwarded to 10.1.1.3; since this network doesn't exist in the routing table, this packet is forwarded to the default route.
  
• A packet destined to 172.30.254.1 is dropped.
  
  Các bạn giải thích hộ minh chấm đầu dòng số 2 với số 4 với,tiện thế chỉ luôn hộ minh cái longest match rule là như thế nào.thank các bạn.