Suppose an ISP owns the block of addresses of the form 200.200.128.0/19. Suppose it wants to create four subnets from this block, with each block having the same number of IP addresses. What are the prefixes (of form a.b.c.d/x) for the four subnets?

Question

rsmith6559 · Answer

4 = 2^2, so your netmask would just increase 2 bits, and the next couple of bits after that would just count 0 - 3 to give you the four subnets.

e.mccormick · Answer

The a.b.c.d/x notation is known as CIDR. There is a chart here: http://en.wikipedia.org/wiki/Classless_Inter-Domain_Routing You can see how it works pretty well from the chart