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Possible Duplicate:
How does Subnetting Work?

what is the last valid host on the subnetwork and how did u get ur answer

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marked as duplicate by Chris S, Shane Madden, squillman, Iain, Evan Anderson Apr 14 '11 at 17:06

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

Smells like homework! – Chris S Apr 14 '11 at 16:47
@ChrisS: Ya' think? How did u get ur answer? – Bart Silverstrim Apr 14 '11 at 17:05
Kid's these days! What do they teach them in school? Apparently not how to do research. "I asked the internet and they told me." – Caleb Apr 14 '11 at 20:06

How Does Subnetting Work Take a look at the mentioned post. It should answer your questions.

For reference though: - Mask of 252 (Block size of 4 (256-252)) In the four Octet. 
A /30 means 30 network bits are "on" (1's) so:

1111 1111.1111 1111.1111 1111.1111 1100 = /30

Looking at the forth octet: 1111 1100 = 252 in Decimal

Your valid subnets increment by the block size... In this case 4

So your valid subnets would then be,,... -> to (.204 is the next subnet) -> first valid host -> last valid host -> Broadcast Address

However, I HIGHLY suggest reading the "How Does Subnetting Work" post.

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