Solved

VLSM question

Posted on 2010-08-23
6
291 Views
Last Modified: 2012-05-10
Hi;

I found this link http://fengnet.com/book/CCNA%20Portable/ch02lev1sec2.html#ch02fig01 to explain how VLSM works, it shows step by step to find out each subnet with using VLSM.  This is a good site so far amongs all others site which explain how VLSM works but I still got lost in Step 2.

In Step 2, the ".64"  is picked for Network "A", why it is not ".0"?

The website author used .128/26 to break it into two for network "B", can he use .192/26 to break it instead of .128/26?  If not, why?

0
Comment
Question by:KANEWONG
  • 3
  • 2
6 Comments
 
LVL 17

Expert Comment

by:Kvistofta
ID: 33503386
0
 
LVL 1

Author Comment

by:KANEWONG
ID: 33503498
Yes, it is right, it will break into 4 subnets like this..

192.168.100.0/26
192.168.100.64/26
192.168.100.128/26
192.168.100.192/26

But why it is picking 192.168.100.64/26 for Network "A", not 192.168.100.0/26?

Also, in step 5 for Serial Link, the author go back to use /26 subnet for the router interface, not keep going to use /28 which is calculated in Step 4.
0
 
LVL 24

Accepted Solution

by:
rfc1180 earned 250 total points
ID: 33503576
>In Step 2, the ".64"  is picked for Network "A", why it is not ".0"?
He could have used .0/26, but he chose not to and decided to use .0/26 to determine network numbers for serial Links.

>The website author used .128/26 to break it into two for network "B", can he use .192/26 to break it instead of .128/26?  If not, why?
Yes he could have used the .192, it is a matter of preference of which one to use.
I typically leave the last (Few of the last subnets alone for growth)

Billy
0
Is Your Active Directory as Secure as You Think?

More than 75% of all records are compromised because of the loss or theft of a privileged credential. Experts have been exploring Active Directory infrastructure to identify key threats and establish best practices for keeping data safe. Attend this month’s webinar to learn more.

 
LVL 1

Author Comment

by:KANEWONG
ID: 33503635
thanks for point it out.  Yes, I looked back the Step 5, the author is using .0/26 to create another subnet for router interface.  This is the reason why, he picked .64/26 in step 2 for Network "A"

Because both of .0/26 and .64/26 creates 62 hosts.  The author can use .0/26 for Network "A" and .64/26 for router interface either, right?
0
 
LVL 17

Expert Comment

by:Kvistofta
ID: 33503642
In ancient times there were limitations in the routers so that the first subnet could not be used. It hasnt been an issue for the last 10 years but maybe that was the reason not to use the .0 subnet? Besides from that it is just a matter of taste which ones to use, all 4 works equally good today.

/Kvistofta
0
 
LVL 17

Expert Comment

by:Kvistofta
ID: 33512041
No points for me?

/Kvistofta
0

Featured Post

Is Your Active Directory as Secure as You Think?

More than 75% of all records are compromised because of the loss or theft of a privileged credential. Experts have been exploring Active Directory infrastructure to identify key threats and establish best practices for keeping data safe. Attend this month’s webinar to learn more.

Question has a verified solution.

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

Suggested Solutions

Title # Comments Views Activity
What is IP Address - Zyxel P660H 12 84
Port forwarding 14 116
error with file_get_contents and unserialize 22 100
Need recommendation for a DNS host provider. 3 83
Creating an OSPF network that automatically (dynamically) reroutes network traffic over other connections to prevent network downtime.
Configuring network clients can be a chore, especially if there are a large number of them or a lot of itinerant users.  DHCP dynamically manages this process, much to the relief of users and administrators alike!
With the power of JIRA, there's an unlimited number of ways you can customize it, use it and benefit from it. With that in mind, there's bound to be things that I wasn't able to cover in this course. With this summary we'll look at some places to go…
Both in life and business – not all partnerships are created equal. As the demand for cloud services increases, so do the number of self-proclaimed cloud partners. Asking the right questions up front in the partnership, will enable both parties …

912 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

Need Help in Real-Time?

Connect with top rated Experts

21 Experts available now in Live!

Get 1:1 Help Now