An ISP is granted a block of classless address starting with 150.80.0.0/16. The
ID: 3832209 • Letter: A
Question
An ISP is granted a block of classless address starting with 150.80.0.0/16. The ISP wants to distribute blocks of addresses to different customer groups as follows:
Customer Group 1: The number of customers in this group is 100. The type of customer is a medium-size business that needs 128 addresses.
Customer Group 2: The number of customers in this group is 200. The type of customer is a small-size business that needs 32 addresses.
Customer Group 3: The number of customer in this group is 1024. The type of customer is a household that needs 8 addresses.
Design the blocks (ranges) for each customer in slash notation. For a,b and c, only show blocks for the 1st, 2nd and last customer.
d.) After a, b, and c are satisfied, how many addresses remain for the ISP?
Explanation / Answer
Customer Group 1:
For this each customer need 128 addresses.No of bits for this is 7 (27 =128) ie suffix length. prefix length is 32-7=25
Customer Group 2:
For this each customer need 32 addresses.No of bits for this is 5 (25=32) ie suffix. prefix length is 32-5=27
Customer Group 3:
For this each customer need 8 addresses.No of bits for this is 3 (23=8). prefix length is 32-3=29
No of unused address from the second last byte is= 255-106=149
Therefore total address remain with IP provider =149*256(last byte)=38144
First Address Last Address First Customer 150.80.0.0/25 150.80.0.127/25 Second Customer 150.80.0.128/25 150.80.0.255/25 Last Customer 150.80.49.128/25 150.80.49.255/25