Solved

subnetting

Posted on 2014-10-03
4
333 Views
Last Modified: 2014-10-03
I'm studying for the Network + test, and for subnetting, I don't have a problem subnetting class C networks, but I'm confused on class B.
the method the book I'm using is to ask 5 questions
how many subnets - the formula is 2 to the X power - x = number of masked bits - no problems there
how many hosts per subnet - formula is 2 to the Y power minus 2    y = number of host per subnet
what art the valid subnets formula is  265 - subnet mask = block size aka increment number   -  now this is what throws me,
so, for example, if i have a class B network and the mask is 255.255.240.0 (/20) i would use the formula
256-240 = 16 so the block size or increment number is 16. in the book, he makes a chart like this

subnet        0.0         16.0              32.0          48.0
first host     0.1         16.1              32.1          48.1
last host     15.254   31.254         47.254      63.254
broadcast   15.255   31.255        47.255       63.255

so does this mean that in the first column for instance. if the address is 172.16.X.Y the first host address is 172.16.0.1 and the last address in subnet 0.0 is 172.16.15.254? which means there are LOTS of hosts?
0
Comment
Question by:JeffBeall
4 Comments
 
LVL 25

Accepted Solution

by:
Ken Boone earned 167 total points
ID: 40360147
Yes that is exactly what it means... It also measn that 172.16.1.0 and 172.16.2.0 and 3.0, etc.. are all host addresses inside that large block.

Now in the real world you would only carve a class B this large to hand out to sub-organizations where it will be chopped up further.  You would never want a flat network that large.

But you got it!
0
 
LVL 26

Assisted Solution

by:Fred Marshall
Fred Marshall earned 167 total points
ID: 40360153
Forget about "classes" for a moment at least.
I don't know why people continue to introduce this archaic term.  Lazy I guess.

But, to answer your question.  Yes.  That's it.  You have interpreted the table correctly.
0
 
LVL 22

Assisted Solution

by:Jody Lemoine
Jody Lemoine earned 166 total points
ID: 40360154
You've got it exactly. The example you gave gives you 4094 hosts per subnet and 16 equally-sized subnets off of your /16.
0
 
LVL 1

Author Closing Comment

by:JeffBeall
ID: 40360289
ok, thank you.
0

Featured Post

Free Tool: SSL Checker

Scans your site and returns information about your SSL implementation and certificate. Helpful for debugging and validating your SSL configuration.

One of a set of tools we are providing to everyone as a way of saying thank you for being a part of the community.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Meet the world's only “Transparent Cloud™” from Superb Internet Corporation. Now, you can experience firsthand a cloud platform that consistently outperforms Amazon Web Services (AWS), IBM’s Softlayer, and Microsoft’s Azure when it comes to CPU and …
An article on effective troubleshooting
Viewers will learn how to properly install and use Secure Shell (SSH) to work on projects or homework remotely. Download Secure Shell: Follow basic installation instructions: Open Secure Shell and use "Quick Connect" to enter credentials includi…
This video gives you a great overview about bandwidth monitoring with SNMP and WMI with our network monitoring solution PRTG Network Monitor (https://www.paessler.com/prtg). If you're looking for how to monitor bandwidth using netflow or packet s…

679 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question