*

Offline junker

  • Planar Moderator
  • *****
  • Posts: 9237
    • View Profile
How to Subnet, an Example
« on: December 07, 2013, 06:13:48 AM »
How to subnet the following IP:
10.96.42.37 /28


1) Determine your subnet mask based on the “slash” or “CIDR” notation (the /28).  It is about which bit is on and off in each octet, which I can explain more if anyone wants.  A quick reference to all relevant IPv4 subnet masks:

/1 - 128.0.0.0
/2 - 192.0.0.0
/3 - 224.0.0.0
/4 - 240.0.0.0
/5 - 248.0.0.0
/6 - 252.0.0.0
/7 - 254.0.0.0
/8 - 255.0.0.0
/9 - 255.128.0.0
/10 - 255.192.0.0
/11 - 255.224.0.0
/12 - 255.240.0.0
/13 - 255.248.0.0
/14 - 255.252.0.0
/15 - 255.254.0.0
/16 - 255.255.0.0
/17 - 255.255.128.0
/18 - 255.255.192.0
/19 - 255.255.224.0
/20 - 255.255.240.0
/21 - 255.255.248.0
/22 - 255.255.252.0
/23 - 255.255.254.0
/24 - 255.255.255.0
/25 - 255.255.255.128
/26 - 255.255.255.192
/27 - 255.255.255.224
/28 - 255.255.255.240
/29 - 255.255.255.248
/30 - 255.255.255.252

So the subnet mask of /28 is 255.255.255.240


2) Determine block size.  Simple, 256 - (the value of the octet you are subnetting in)

   In this case, “256 - 240” which is 16


3) Determine the network address of the subnet.  This is the first IP in the subnet, but it is not useable.  Start at 0, then count by the block size until you reach the range of the octet you are subnetting in.  In this case /28 is in the last octet, so based on IP 10.96.42.37 you are trying to find the range where .37 falls.  0, 16, 32, 48…  .37 falls in between 32 and 48, so 32 is the network address, more specifically 10.96.42.32 is the network address.


4) Determine the broadcast address of the subnet.  This is always the IP before the next network address.  Since, in step 3 we determined 10.96.42.32 is a network address, and 10.96.42.48 is the next network, 10.96.42.47 is the broadcast address.  The broadcast address is also not a useable IP.


5) Determine the number of useable host IPs.  Easy step…  (2^n)-2 where n = 32 - (the CIDR number).  In this case, 2^(32-28)-2=14.  It makes sense, the block size is 16, so there are 16 IPs in the subnet, you can’t use the network address or the broadcast address, so subtract 2.


6) Determine the useable host range.  Steps 3 and 4 are great, but you can’t use the IP addresses.  So, find out what you can use.  This is easy, the range starts at the IP after the network address, and ends at the IP before the broadcast address.  So, in this instance, the useable range is 10.96.42.33-10.96.42.47.



I have no idea why I posted this, but if you have any questions, or want to know more about networking in general please ask.


DISCLAIMER:  I AM NOT QUALIFIED
« Last Edit: December 07, 2013, 04:06:19 PM by junker »

Saddam Hussein

Re: How to Subnet, an Example
« Reply #1 on: December 07, 2013, 06:16:05 AM »
How do I use YouTube to hack a website?

*

Offline junker

  • Planar Moderator
  • *****
  • Posts: 9237
    • View Profile
Re: How to Subnet, an Example
« Reply #2 on: December 07, 2013, 06:17:05 AM »
How do I use YouTube to hack a website?

THAT IS OUTSIDE OF THE SCOPE OF THIS THREAD

I AM NOT QUALIFIED

*

Offline jroa

  • *
  • Posts: 3094
  • Kentucky Gentleman
    • View Profile
Re: How to Subnet, an Example
« Reply #3 on: December 07, 2013, 06:22:21 AM »
junker, good job.  My only suggestion would be to actually explain the purpose of a subnetwork, what the subnet mask does as far as dividing a network up, and a little better explanation on how the subnets interact with the networks. 

*

Offline junker

  • Planar Moderator
  • *****
  • Posts: 9237
    • View Profile
Re: How to Subnet, an Example
« Reply #4 on: December 07, 2013, 06:32:41 AM »
junker, good job.  My only suggestion would be to actually explain the purpose of a subnetwork, what the subnet mask does as far as dividing a network up, and a little better explanation on how the subnets interact with the networks.

Oh, fuck that.  If people have questions, they can ask and I will answer.

You subnet to get IPs.  I can also teach you all about the OSI, especially layers 2 and 3.  I am a pro, almost qualified.

Offline bj1234

  • *
  • Posts: 112
    • View Profile
Re: How to Subnet, an Example
« Reply #5 on: December 07, 2013, 06:35:56 AM »
How does subnetting let me hack youtube videos?

*

Offline la xasop

  • Administrator
  • *****
  • Posts: 6284
  • Professional computer somebody
    • View Profile
Re: How to Subnet, an Example
« Reply #6 on: December 07, 2013, 06:48:03 AM »
You subnet to get IPs.  I can also teach you all about the OSI, especially layers 2 and 3.  I am a pro, almost qualified.

Can you teach me about layer 6? It's the one I know least about.
when you try to mock anyone while also running the flat earth society. Lol

*

Offline junker

  • Planar Moderator
  • *****
  • Posts: 9237
    • View Profile
Re: How to Subnet, an Example
« Reply #7 on: December 07, 2013, 06:49:54 AM »
You subnet to get IPs.  I can also teach you all about the OSI, especially layers 2 and 3.  I am a pro, almost qualified.

Can you teach me about layer 6? It's the one I know least about.

lol no one uses presenation layer willingly

*

Offline la xasop

  • Administrator
  • *****
  • Posts: 6284
  • Professional computer somebody
    • View Profile
Re: How to Subnet, an Example
« Reply #8 on: December 07, 2013, 06:59:31 AM »
lol no one uses presenation layer willingly

How would you know? You're not qualified.
when you try to mock anyone while also running the flat earth society. Lol

*

Offline junker

  • Planar Moderator
  • *****
  • Posts: 9237
    • View Profile
Re: How to Subnet, an Example
« Reply #9 on: December 07, 2013, 07:01:33 AM »
lol no one uses presenation layer willingly

How would you know? You're not qualified.

I know :(

*

Offline jroa

  • *
  • Posts: 3094
  • Kentucky Gentleman
    • View Profile
Re: How to Subnet, an Example
« Reply #10 on: December 07, 2013, 07:20:15 AM »
Can I subsnets with IVP6? ???

*

Offline junker

  • Planar Moderator
  • *****
  • Posts: 9237
    • View Profile
Re: How to Subnet, an Example
« Reply #11 on: December 07, 2013, 07:27:45 AM »

*

Offline jroa

  • *
  • Posts: 3094
  • Kentucky Gentleman
    • View Profile
Re: How to Subnet, an Example
« Reply #12 on: December 07, 2013, 07:45:12 AM »
Please explain. 

*

Offline Lord Dave

  • *
  • Posts: 5760
  • Grumpy old man.
    • View Profile
Re: How to Subnet, an Example
« Reply #13 on: December 07, 2013, 02:07:44 PM »
I used to know this stuff but its been years.  Thanks for the refresher.

*

Offline junker

  • Planar Moderator
  • *****
  • Posts: 9237
    • View Profile
Re: How to Subnet, an Example
« Reply #14 on: December 07, 2013, 04:02:56 PM »
Please explain.

https://supportforums.cisco.com/docs/DOC-17232

Cisco does it better.

This thread is based on IPv4 which I am nearly qualified in.  Keep questions related to that.  I can only hope to be qualified on IPv6 in the coming decades.

*

Offline Rushy

  • Planar Moderator
  • *****
  • Posts: 7238
    • View Profile
Re: How to Subnet, an Example
« Reply #15 on: December 07, 2013, 11:28:30 PM »
How do I brute force AES-256?

*

Offline junker

  • Planar Moderator
  • *****
  • Posts: 9237
    • View Profile
Re: How to Subnet, an Example
« Reply #16 on: December 07, 2013, 11:32:08 PM »
How do I brute force AES-256?

A lot of super computers, and a lot of time.

*

Offline Rushy

  • Planar Moderator
  • *****
  • Posts: 7238
    • View Profile
Re: How to Subnet, an Example
« Reply #17 on: December 07, 2013, 11:36:21 PM »
A lot of super computers, and a lot of time.

Well, you're not wrong.

*

Offline junker

  • Planar Moderator
  • *****
  • Posts: 9237
    • View Profile
Re: How to Subnet, an Example
« Reply #18 on: December 07, 2013, 11:42:20 PM »
A lot of super computers, and a lot of time.

Well, you're not wrong.

I am also not qualified.