1. A block of addresses 146.157.224.0/19 was granted to an ISP. These addresses were allocated to three groups of customers. Subblock #1 was allocated to the 1st group of 20 customers, each of which needs 126 assignable addresses. Subblock #2 was allocated to the 2nd group of 15 customers, each of which needs 126 assignable addresses. Subblock #3 was allocated to the 3rd group of 12 customers, each of which needs 64 addresses. Find the subblocks, masks and range of addresses for: a. subblock #1

b. subblock #2

c. subblock #3

d. 12th customer of the 1st group

e. 7th customer of the 2nd group

f. 10th customer of the 3rd group

g. How many addresses are still available after this allocation? 2. The 33rd address of a block allocated to an organization is 145.154.85.160. The organization needs a total of 123 addresses for hosts and 3 routers. Find the mask and define this block of addresses. Is there any wastage of the IP addresses? If yes, how many addresses are wasted?