Unofficial LTT Subnetting Guide.

[SOUTHwarrior]

Okay so as the title suggests I am working on a subnetting guide to help out some of the newer people into networking because here recently I have been seeing quite a few posts about what networks to use and how to do this and that with ip address. So after I finish my subnetting guide I will start working on a How-to ip addresses Guide covering all the topics of how to convert from binary to decimal, octets, and basic subnet masks.

 

Topics I am covering is main vocabulary such as vlsm, classless, classful, and CIDR. Ovbiously I am including information about the subnet mask, network/host range, Broadcast and network addresses and such.

 

IF there is anything you would want me to add Comment below. I should be adding my rough draft here soon and I want you guys to give it an overview and if you see anything I could work on to make it an easier read Let me know. 

 

Thanks for reading this. Like I said I will be adding the rough draft here in the next 2-3 days. It would be sooner but between work and school I dont really have that much time to work on it.

 

So heres what I have so far. Sorry for taking so long getting it posted. I have been side tracked with school the past few weeks.

 

Linus Tech Tips Unofficial

Subnetting Guide and

How To

What is a subnet?

            A subnet is basically making a network out of a network. Say for instance you have a private class C network and you want to make two networks out of the same address space. You can do this neat thing called Subnetting. What this lets you do is separate a network range into multiple networks depending on the range of address you have. That may sound difficult but its pretty easy and just requires a little bit of know how and by the time you read this you should be more capable of subnetting your own network address range.

 

Terms and Lingo

VLSM - Variable Length Subnet Mask

CIDR – Classless Inter-Domain Routing

Classful - Goes by the standard subnet masks for that address Class

Classless – Use any subnet mask you want

Subnet Mask – The identifier that separates Network and Host Bits.

 

Basics

            Below posted is a VLSM chart. Learn this. Memorize it. Learn to love it. Then when you remember it you can repeat it.

This chart will help you in more ways than one.

First you can look at all the funny numbers with a / in front of them. This is referred to as CIDR notation. This corresponds with your subnet mask and the amount of bits you use for the network portion.

11111111.11111111.11111111.00000000

11000000.10101000.00000001.00000001

This is a regular Class C private ip address converted to binary Notice how there is 4 Octets each containing 8 bits a piece. This would give you a CIDR of /24 and a subnet mask of 255.255.255.0 which is the regular subnet mask for a class C address. This is also a classful address. What you’re reading this for is how to do classless addressing

Secondly what this chart will help you with is the range of address you can use. A typical class C address uses 0-255. With 0 being your network address and 255 being your broadcast. So whenever you go through the ip address ranges you always subtract two so you are able to calculate the amount of available hosts that the network can actually use because the first and last address are reserved for those two purposes.

[Raboo]

Cool idea

[CCap]

I like the thought and would love to learn more about networking. Can't wait for the final draft!

[LAwLz]

Sorry but I don't really see the point. General consumers (99.9% of this forum) doesn't need it, and the people who do need to know it will already know it.

It's a nice idea, but not really that useful on here.

[Darren]

Adjusting subnets is not something that consumers will do. I don't see your average household with more than 250 devices

[SOUTHwarrior]

Sorry but I don't really see the point. General consumers (99.9% of this forum) doesn't need it, and the people who do need to know it will already know it.

It's a nice idea, but not really that useful on here.

I know most people on here wont need it but its more of a general guide for people that pass by and want to get a bit of knowledge about the subject. Many a time have I seen people asking why their network doesnt work when they put every device on the network with the same ip address or set a broadcast address on their router and cant figure out why its not working. Just a helpful guide for people to read :-p

[Raphael_123]

Sorry but I don't really see the point. General consumers (99.9% of this forum) doesn't need it, and the people who do need to know it will already know it.

It's a nice idea, but not really that useful on here.

The idea is good but I agree with this guy

[SOUTHwarrior]

Update has been added. Enjoy. Still working on it.

[Blade of Grass]

Why even talk about classful domain addressing (class A, B, C)? We've moved away from that and now go by CIDR block notation (192.168.1.1/24 etc).

 

Also, why talk about VLSM?

 

Not to shit on your post or anything, but I think you should make the guide for this site's target audience - home readers. IT professionals have Spiceworks etc for IT related stuff. Overall, it's a good post, but I'm not sure about the validity of using it for home users.

[SOUTHwarrior]

Why even talk about classful domain addressing (class A, B, C)? We've moved away from that and now go by CIDR block notation (192.168.1.1/24 etc).

 

Also, why talk about VLSM?

 

Not to shit on your post or anything, but I think you should make the guide for this site's target audience - home readers. IT professionals have Spiceworks etc for IT related stuff. Overall, it's a good post, but I'm not sure about the validity of using it for home users.

Classful addressing still exists? I mean it is a building base for everything you'd learn in networking. I wouldnt think they would teach it if it wasnt needed.

VLSM is a part of subnetting? Edit: I also am going to cover CIDR more in depth. This is just the first rough draft thats not even done yet.

And I just felt like putting something up for people to have a good read and if they had a question they could probably figure out what they are needing to know pretty simply by reading through it.

[Blade of Grass]

Classful addressing still exists? I mean it is a building base for everything you'd learn in networking. I wouldnt think they would teach it if it wasnt needed.

VLSM is a part of subnetting? Edit: I also am going to cover CIDR more in depth. This is just the first rough draft thats not even done yet.

And I just felt like putting something up for people to have a good read and if they had a question they could probably figure out what they are needing to know pretty simply by reading through it.

Well if you want to start from the building blocks, why not talk about subnet masks? Broadcasting addresses? How broadcast addresses work with multiple subnets?

I'm just saying, you seemed to have started with a little basics, and then jump into VLSM, without covering the basic knowledge that is essential for understanding the advanced stuff.

[SadTech]

Sorry but I don't really see the point. General consumers (99.9% of this forum) doesn't need it, and the people who do need to know it will already know it.

It's a nice idea, but not really that useful on here.

 

General Knowledge especially about networking is very useful. Subnetting can be tricky. A lot of people on here are going to school or have jobs in IT. I am a network admin. and at my job I subnet quite a bit, nice to have a easy to reference guide. When I was in college we had subnetting questions all the damn time. If this helps even one person then it was worth it for him to post.

 

But home users wont use it, and if they do....WOW.

 

There are still enough kids in school on here and kids who have jobs as IT professionals that this could very well be useful..

 

I congratulate you SOUTHwarrior! I really don't understand why everyone is shitting on you for posting this....

 

for all the people hating you don't have to click on the thread and read it.... just because there is Spiceworks etc doesn't mean people won't find it useful on here.

 

I am just dumbfounded by all the hate he is receiving. 

[SOUTHwarrior]

Well if you want to start from the building blocks, why not talk about subnet masks? Broadcasting addresses? How broadcast addresses work with multiple subnets?

I'm just saying, you seemed to have started with a little basics, and then jump into VLSM, without covering the basic knowledge that is essential for understanding the advanced stuff.

Rough Draft. Not Final production. Thats why I asked at the beginning of the post for some things the users think that would make it better.

General Knowledge especially about networking is very useful. Subnetting can be tricky. A lot of people on here are going to school or have jobs in IT. I am a network admin. and at my job I subnet quite a bit, nice to have a easy to reference guide. When I was in college we had subnetting questions all the damn time. If this helps even one person then it was worth it for him to post.

 

But home users wont use it, and if they do....WOW.

 

There are still enough kids in school on here and kids who have jobs as IT professionals that this could very well be useful..

 

I congratulate you SOUTHwarrior! I really don't understand why everyone is shitting on you for posting this....

 

for all the people hating you don't have to click on the thread and read it.... just because there is Spiceworks etc doesn't mean people won't find it useful on here.

 

I am just dumbfounded by all the hate he is receiving. 

Thank you. I have seen countless times on here when somebody has posted something asking about what a subnet is and why their 10.10.10.0/24 ip wont work on their 192.168.1.0/24 network. Just trying to help out the people starting out in the IT world.

[stefan32burke]

Yeah im just starting system technology L5, and they cover networking, so I really appreciate the opportunity to study and learn as much as I can now. Thanks SOUTHwarrior, I look forward to reading more of your posts.

[Darren]

Classful addressing still exists? I mean it is a building base for everything you'd learn in networking. I wouldnt think they would teach it if it wasnt needed.

VLSM is a part of subnetting? Edit: I also am going to cover CIDR more in depth. This is just the first rough draft thats not even done yet.

And I just felt like putting something up for people to have a good read and if they had a question they could probably figure out what they are needing to know pretty simply by reading through it.

 

Err classes were a thing when they were first handing out addresses. Your companies such as Ford, Bell labs, large ISPs got 'Class A' allocations (/8), Universities, mid sized companies got Class B networks (/16) and smaller entities were given out Class C (/24). Also, more strictly...

 

Class A addresses begin with 0 (bitwise)

• 0.0.0.0/8 to 127.0.0.0/8

• Class B addresses begin with 10

• 128.0.0.0/16 to 191.0.0.0/16

• Class C addresses begin with 110

• 192.0.0.0/24 to 223.0.0.0/24

• Class D addresses begin with 1110

• 224.0.0.0 to 239.0.0.0

• Class E addresses begin with 1111

• 240.0.0.0 to 255.0.0.0

 

Everything is in CIDR notation now anyway since 1993, so I'm not sure why this is still being brought up.

 

To be fair though, this isn't really needed since this subforum is more of a "Please help me make a decision on what to buy" or "do i need x" or "help my internet sux". This doesn't seem like the place to come if you intend on learning any networking theory.