Networks

Ask something
Discussion Locked

Classless Subnetting!!! Network+

0 helpful
2 replies

by diazolidineyl 1 view

Closed to new repliesThis discussion is closed. It stays readable, but it takes no new replies.

Okay, the concept with classless subnetting works fine in my head. I can deal with it, but its when I start to actually try it I'm lost. Here is a specific problem I have. This is in preparation for the network+, so if anyone elaborates, please make sure it's understandable for some one who has only their A+ cert.

The private class B address range 172.16.0.0/12 -172.31.255.254 has a 12-bit network id and 20 bit host id. I'm fine with that.

In binary it would look like

10101100.0001||000.00000000.00000000

( The two pipes denote where the subnet mask ends)

I'm fine with that too ( if its correct).

But what would the subnet mask look like if were numerical value? would it be 255.16.0.0?? or would be 255.224.0.0? Also how would I calculate how many hosts or subnets there would be. I'm not even sure if I'm explaining this right (I'm self teaching out of a book, and if I ask the book a question it doesn't respond back!) So if anyone would be kind enough to explain this to me in simple terms it would be much appreciated!

Many Thanks in advance!

2 replies

by deepsand

Try the "Questions" forum; the "Discussion" forum is for matters of general discussion, not specific problems in search of a solution.

Post problems such as this to the "Question" forum, rather than the "Discussion" forum. There are those who specifically seek out problems in need of a solution, and that's where they go to look for such.

Additionally there are the benefits that:

1) The "Questions" forum provides for your feedback, by way of your being able to mark "helpful" responses as such. This does not necessarily mean that a given response contained the complete solution to your problem, but only that it served to guide you toward it. This is intended to serve as an aid to those who may in the future have a problem similar to yours, so that they might have a ready source of reference available, thereby perhaps obviating the need for them to repeat questions previously asked and answered.

2) The revised TR makes it quite difficult to find both "Discussions" and "Questions" that have not had a fairly recent post, owing to some functions comingling them in the listings. By keeping each type in their respective forums, it is easier for all to find what they are looking for.

by michael kassner

Subnetting can be frustrating to be sure. What book or reference are you using now? TechRepublic's David Davis has a good article and starting point for learning about subnetting. There are also several links to good websites in the article that will further your understanding of classless subnetting.

http://articles.techrepublic.com.com/5100-1035_11-5778292.html

This next link is one that I especially appreciate as it allows me to practice what I have learned.

http://www.subnettingquestions.com/default_uk.asp

This discussion is closed to new replies.