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Beginner

How do I assign subnet IDs? Working through CCENT labs ch 17

I'm working through the CCENT labs and I'm confused how they are assigning subnets. I've pasted the instructions and Table 1 (what I have to complete) and Table 3 (the answers) below. 

 

I understand why the lowest subnet for network 10.0.0.0/24 is 10.0.0.0 (subnet 1), but why is the lowest and next available subnet for 10.0.0.0/25 (subnet 2) assigned 10.0.1.0 and not 10.1.0.0 or 10.0.0.1? Is this a matter of preference? Could I assign these 7 subnets like: 10.0.0.0, 10.1.0.0., 10.2.0.0., etc?

 

subnettingInstructions.PNGsubnetting1.PNGsubnetting2.PNG

 

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2 ACCEPTED SOLUTIONS

Accepted Solutions
Hall of Fame Guru

Re: How do I assign subnet IDs? Working through CCENT labs ch 17

 

You can't use 10.0.0.1 because that is part of 10.0.0.0/24 and 10.0.0.0/25 is also part of 10.0.0.0/24 so that is not useable either. 

 

The question is really saying what is the next available subnet after 10.0.0.0/24 and that has to be 10.0.1.0 because you have used up the whole of the 10.0.0.0/24 subnet already. 

 

You could use 10.1.0.0 etc. but then the subnets would not follow on from each other ie. between 10.1.0.0/24 and 10.0.0.0/24 there are a lot of available /24s to use. 

 

Jon

 

Collaborator

Re: How do I assign subnet IDs? Working through CCENT labs ch 17

Hi,
I am not sure that I can explain or not. But Try to understand the question:
There is many points are hidden in the above question:

1: What subnet is offered to you: 10.0.0.0/8

2. What is R1 LAN Subnet: 10.0.0.0/24 means from IP Address: 10.0.0.1 to 10.0.0.254

3. Now what is next available subnet from the given subnet: 10.0.1.0 

4. So R3 LAN Subnet will be: 10.0.1.0/25 means 10.0.1.1 to 10.0.1.126

 

Regards,

Deepak Kumar

 

5 REPLIES
Hall of Fame Guru

Re: How do I assign subnet IDs? Working through CCENT labs ch 17

 

You can't use 10.0.0.1 because that is part of 10.0.0.0/24 and 10.0.0.0/25 is also part of 10.0.0.0/24 so that is not useable either. 

 

The question is really saying what is the next available subnet after 10.0.0.0/24 and that has to be 10.0.1.0 because you have used up the whole of the 10.0.0.0/24 subnet already. 

 

You could use 10.1.0.0 etc. but then the subnets would not follow on from each other ie. between 10.1.0.0/24 and 10.0.0.0/24 there are a lot of available /24s to use. 

 

Jon

 

Beginner

Re: How do I assign subnet IDs? Working through CCENT labs ch 17

So is 10.0.1.0 considered a lower number, and that is why 10.1.0.0 is wrong?

Hall of Fame Guru

Re: How do I assign subnet IDs? Working through CCENT labs ch 17

 

To be honest Cisco questions are never really that clear to me. 

 

I took it to mean use the next available subnet after 10.0.0.0/24 and that is 10.0.1.0/24. 

 

Jon

Collaborator

Re: How do I assign subnet IDs? Working through CCENT labs ch 17

Hi,
I am not sure that I can explain or not. But Try to understand the question:
There is many points are hidden in the above question:

1: What subnet is offered to you: 10.0.0.0/8

2. What is R1 LAN Subnet: 10.0.0.0/24 means from IP Address: 10.0.0.1 to 10.0.0.254

3. Now what is next available subnet from the given subnet: 10.0.1.0 

4. So R3 LAN Subnet will be: 10.0.1.0/25 means 10.0.1.1 to 10.0.1.126

 

Regards,

Deepak Kumar

 

Hall of Fame Master

Re: How do I assign subnet IDs? Working through CCENT labs ch 17

It seems to me that the key to this discussion is the instruction that in assigning subnets the lowest available subnet should be used. After you have used 10.0.0.0/24 then the lowest available subnet is 10.0.1.0.

 

And yes 10.0.1.0 is considered a lower number that 10.1.0.0.

 

HTH

 

Rick

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