IT 120 Spring 2016 Homework 3 | Complete Solution

IT 120
Spring 2016
Homework 3

1.    (8pts) Assume that NJIT has a CIDR address space 92.145.72.0/22.  Which of the following addresses could be valid host addresses within that space? Of the ones that are not within the space explain why.
a.    92.145.102.20
b.    92.145.75.255
c.    92.145.76.36
d.    92.145.79.1

2.     (9pts) An ISP has CIDR block 204.160.0.0/12.  The ISP wants to create 19 sub-blocks from this block.  
a.    How many bits should the ISP add to the mask for the sub-blocks?  
b.    What are the addresses (include slash notation) for each sub-block?
c.    What is the maximum number of valid hosts in each sub-block?

3.    (9pts) A CIDR block extends from 11.13.248.0  to  11.13.255.255.
a.    How many bits are in the net id?
b.    How many bits are in the host id?
c.    What is the mask in binary, dotted decimal, and slash notation?

4.    (10pts) We want to assign a CIDR block of 512 addresses (including all 0’s and all 1’s), starting at 92.145.72.0.
a.    What is the maximum address in this block?  [Hint:  figure out how many bits are required to represent 512 hosts.  The maximum address is when all those bits are 1]
b.    How many bits are in the host id for the new CIDR block?
c.    How many bits are in the net id for the new CIDR block?
d.    What is the mask in binary, dotted decimal, and slash notation?

5.     (15pts) Suppose you are an ISP that owns a /14 address CIDR block starting 92.184.0.0/14.
a.    Show the new subnet mask you would use to allocate address blocks to 10 customers who need addresses for a minimum 80 computers but they do not want exceed 126 computers.
b.    Provide the start and end addresses for the 6 CIDR blocks created for each of the customers.
c.    How many remaining IP addresses do you have to allocate to new customers?

EXTRA CREDIT (6pts)
1.    Broadcasting won’t work for the Internet. Describe how IP addressing allows it to communicate between LANs without using broadcasting.