Subnet sorrow

Hi all

Im finishing off the subnetting chapter on the cisco press book and I can do all the excercises on the book now i just need to understand how to interpret the answers i get.

This could be a dumb question but.

lets say I get the ip 10.100.18.18 255.248.0.0

I can get the:
subnet no. 10.96.0.0
1st usable ip 10.96.0.1
last usable 10.103.255.254
broadcast 10.193.255.255

So does that mean the ip address spans subnet 10.96.0.1 + subnet 10.97.0.1 and so on up to and including 10.103.255.255

meaning that this ip occupies 7 different subnets!!

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Comments

miller811

celtic_tiger wrote: »

Hi all

Im finishing off the subnetting chapter on the cisco press book and I can do all the excercises on the book now i just need to understand how to interpret the answers i get.

This could be a dumb question but.

lets say I get the ip 10.100.18.18 255.248.0.0

I can get the:
subnet no. 10.96.0.0
1st usable ip 10.96.0.1
last usable 10.103.255.254
broadcast 10.193.255.255

So does that mean the ip address spans subnet 10.96.0.1 + subnet 10.97.0.1 and so on up to and including 10.103.255.255

meaning that this ip occupies 7 different subnets!!

no it means exactly exactly what you described below minus the typo

1st usable ip 10.96.0.1
last usable 10.103.255.254
broadcast 10.103.255.255

that is the subnet (one and only) and includes those addresses.

Even though is moves through the
10.96
10.97
10.98
10.99
10.100
10.101
10.102
10.103

it is still in the same subnet

/13 for the network portion and a /19 for the host bits.
which means that there are 524288 hosts in the subnet 10.96.0.0

with an address range that big, it could be further subnetted if desired, but the question at hand is to be able to identify and understand the question at hand.

hope that helps

have you looked at this link?

http://www.techexams.net/forums/ccna-ccent/38772-subnetting-made-easy.html

test your skills here
IP Subnet Practice

click the new problem button and then solve the question.
repeat, repeat, repeat

Your goal is to be able to subnet in your head when you finish.

comptech+

Re: previous question. If you are starting with the address 10.0.0.0 255.0.0.0 and you need 7 subnets. Your addresses will be 10.0.0.0 - 10.30.255.254 and a broadcast of 10.31.255.255 then the next network of 10.32.0.0 - 10.62.255.254 with a broadcast of 10.63.255.255 then the next network of 10.64.0.0 - 10.94.255.254 with a broadcast of 10.95.255.255 and so forth. All the way up to 10.224.0.0, so your ranges would be 10.0.0.0/27 10.32.0.0/29 10.64.0.0/27 10.96.0.0/27 10.128.0.0/27 10.160.0.0/27 10.192.0.0/27 10.224.0.0/27 and the subnet mask of 10.224.255.255 I think this is your answer.

thenjduke

Miller is right when comes to this problem. Remember the broadcast address is the next ip before the next subnet.

miller811 wrote: »

no it means exactly exactly what you described below minus the typo

1st usable ip 10.96.0.1
last usable 10.103.255.254
broadcast 10.103.255.255

that is the subnet (one and only) and includes those addresses.

Even though is moves through the
10.96
10.97
10.98
10.99
10.100
10.101
10.102
10.103

it is still in the same subnet

/13 for the network portion and a /19 for the host bits.
which means that there are 524288 hosts in the subnet 10.96.0.0

with an address range that big, it could be further subnetted if desired, but the question at hand is to be able to identify and understand the question at hand.

hope that helps

have you looked at this link?

http://www.techexams.net/forums/ccna-ccent/38772-subnetting-made-easy.html

test your skills here
IP Subnet Practice

click the new problem button and then solve the question.
repeat, repeat, repeat

Your goal is to be able to subnet in your head when you finish.

celtic_tiger

Thanks for the replies.

So I think that lets say there are x amount of subnets created with this mask and then this ip 10.103.18.18 /14 is located within the block of ip's below which is one of those subnet ranges?

10.96
10.97
10.98
10.99
10.100
10.101
10.102
10.103

Am I right?

miller811

celtic_tiger wrote: »

Thanks for the replies.

So I think that lets say there are x amount of subnets created with this mask and then this ip 10.103.18.18 /14 is located within the block of ip's below which is one of those subnet ranges?

10.96
10.97
10.98
10.99
10.100
10.101
10.102
10.103

Am I right?

Not sure if you are grasping it....

once the mask becomes a /14 or .252, the block size is now only 4 bits....
so with the address 10.103.18.18 /14 it resides on the 10.100.0.0 subnet
first host 10.100.0.1
last host 10.103.255.254
broadcast 10.103.255.255

next available subnet starts at
10.104.0.0
10.108.0.0
10.112.0.0
10.116.0.0

celtic_tiger

Ah I see it now, just re read your first post after a nights sleep. 1 subnet & multiple ip addresses per subnet. No of subnets depends on the subnet bits in mask.

Dont know why i could'nt se that before. Some days my head just doesnt work.

Thanks.