how to do subnetting?

[aminios1988]

Hello guys,

I was given 192.168.11.0 network, and was asked to create a fixed length logical addressing map to allow for the potential of 6 subnets.

This is what I have done:
1. borrow 3 bits
2. 2^3 = 8 subnets
3. subnet mask: 255.255.255.224

the problem is I was asked for 6 subnets only, so which 2 for them are not usable?

Thank you!

 

[timberdoodle]

They are all usable.....it doesn't have to work out exactly.

 

[Liger88]

the problem is I was asked for 6 subnets only, so which 2 for them are not usable?

They are all usable, which ones to use are entirely up to you. If it was an assignment, and unless otherwise specified, always name from beginning to end of what you need for the network. If it is a real life situation there might be a reason to reserve either the first, last, or even middle subnets when there are extra for management and other LAN specific uses.

Subnetting always goes to the power of 2 so often times you'll have excess host IP's or subnets that go unused but are necessary to obtain the proper mask.

Cheers.

 

[aminios1988]

Thanks! I guess I know what to do now

 

[trick0502]

Hello guys,

I was given 192.168.11.0 network, and was asked to create a fixed length logical addressing map to allow for the potential of 6 subnets.

This is what I have done:
1. borrow 3 bits
2. 2^3 = 8 subnets
3. subnet mask: 255.255.255.224

the problem is I was asked for 6 subnets only, so which 2 for them are not usable?

Thank you!

it is binary bits

so:
255=11111111 (eight 1's)
the last 5 would be 0's (11100000=224)
this would allow for six separate (or eight) networks with 30 host each.

 

[jjeff1]

Keep in mind that unless you're working someplace where you have a limited number of IP addresses; eg you're working with public IP space, you will never subnet like this.

On a private network, you have an entire class A, use it.

 

[timberdoodle]

Keep in mind that unless you're working someplace where you have a limited number of IP addresses; eg you're working with public IP space, you will never subnet like this.

On a private network, you have an entire class A, use it.

Well, I don't know if I would say never.

You will be using VLSM somehow to setup vlans, especially with a class A.
I wouldn't setup a point to point WAN connection with a remote office with anything more than a /30
Voip and wifi often have /23 subnets.
If you do use a class A - meaning 10.0.0.0/8 there is at least a chance that you will join with another company that also uses that subnet range and have to restructure one of them.

What you probably meant was it is generally speaking not a good idea to break up a network with so many subnets for the simple fact that in a year you will decidedly have twice as many devices as you thought you would and run out of IP addresses in whatever subnet it is. Most of the time it easy easier to create /24 subnets per lan or vlan even for a few hosts. It makes it easy for future expansion and it makes it easier for vlan segments and network management. Regardless OP you need to know how to do this inside and out for your network certs which I assume this post is regarding and you are on the right track.