Supernetting 2

[ElijahBaley]

Hi,

After getting a bit confused in another thread I now understand that what they were dealing with there was 'Supernetting' (not subnetting) borrowing bits from the network portion of a address to create a inclusive range of addresses from the pool of the merged class C networks.

At first glance I thought the example below was a error, class C address with a class b subnet mask, So my question is, how can I identify the 4 subnets and the combined host range from the ip address and supernet mask below?

IP Address……………..192.168.35.4
Subnet Mask……………255.255.252.0

Thanks for any help,

 

[ajcazz]

Hi ElijaBailey,
Here is the short answer :

Subnet 1 = 192.168.32.0, Range 192.168.32.1 - 192.168.32.254, Broadcast 192.168.32.255
Subnet 2 = 192.168.33.0, Range 192.168.33.1 - 192.168.33.254, Broadcast 192.168.33.255
Subnet 3 = 192.168.34.0, Range 192.168.34.1 - 192.168.34.254, Broadcast 192.168.34.255
Subnet 4 = 192.168.35.0, Range 192.168.35.1 - 192.168.35.254, Broadcast 192.168.35.255

What you want to know is how do you get to this point!!
Firstly, I write out the subnet in binary, splitting the host from the subnet - eg 192.168.001000 | 00.00000000
Then you can get the four subnets - eg | 01.00000000/10.00000000/11.00000000. Then it is easy to fill int the host range and the broadcast address.

Hope this helps
ajcazz

 

[ElijahBaley]

Thanks acjazz

I think I get it!

192.168.001000|00.00000000 - 32.0
192.168.001000|01.00000000 - 33.0
192.168.001000|10.00000000 - 34.0
192.168.001000|11.00000000 - 35.0

Any chance you could throw a few at me to practise with


Best regards

 

[ajcazz]

Hi ElijaBailey,

No problem - try a few simple ones first.

List the subnet, range of usable addresses and the broadcast address for the following subnets only:

IP 192.168.71.5, subnet mask 255.255.252.0

No a bit harder :

IP 172.116.17.231, Subnet 255.255.240.0

Hint - you will only list one subnet and broadcast address for each problem.

ajcazz

 

[ElijahBaley]

Hi acjazz

Thanks for your help,

I have answered the first question below, but am unsure of the second one - should it read

192.116.12.231

and not

172.116.17.231

or is it a class B address using traditional subnetting

Subnet 172.116.16.0
First Host 172.116.16.1
Last Host 172.116.31.254
Broadcast 172.116.31.255

----------------------------------------------------
'List the subnet, range of usable addresses and the broadcast address for the following subnets only:

IP 192.168.71.5, subnet mask 255.255.252.0'
----------------------------------------------------

192.168.010001|00.00000000 = 68.0
192.168.010001|01.00000000 = 69.0
192.168.010001|10.00000000 = 70.0
192.168.010001|11.00000000 = 71.0

Subnet 192.168.68.0
First Host 192.168.68.1
Last Host 192.168.71.254
Broadcast 192.168.71.255

Im I right in thinking that in these circumstances the merged subnet and broadcast addresses could be used as hosts:

192.168.68.255
192.168.69.0
192.168.69.255
192.168.70.0
192.168.70.255
192.168.71.0

Thanks again,

 

[ElijahBaley]

Ok, here's the second one (I think)
----------------------------------------------------
List the subnet, range of usable addresses and the broadcast address for the following subnets only:

IP 192.116.17.231, Subnet 255.255.240.0
----------------------------------------------------

192.116.0001|0000.00000000 = 16.0
192.116.0001|0001.00000000 = 17.0
192.116.0001|0010.00000000 = 18.0
192.116.0001|0011.00000000 = 19.0
192.116.0001|0100.00000000 = 20.0
192.116.0001|0101.00000000 = 21.0
192.116.0001|0110.00000000 = 22.0
192.116.0001|0111.00000000 = 23.0
192.116.0001|1000.00000000 = 24.0
192.116.0001|1001.00000000 = 25.0
192.116.0001|1010.00000000 = 26.0
192.116.0001|1011.00000000 = 27.0
192.116.0001|1100.00000000 = 28.0
192.116.0001|1101.00000000 = 29.0
192.116.0001|1110.00000000 = 30.0
192.116.0001|1111.00000000 = 31.0

Subnet 192.116.16.0
First Host 192.116.16.1
Last Host 192.116.31.254
Broadcast 192.116.31.255

 

[ajcazz]

You got it!!!
Well done.
When you do the exam, Cisco will try to trick you into picking the wrong network by giving you a list of ones that look correct but are not - be careful take your time and work it out - these are the easy ones that go well towards a passing score.

Any other questions? issues?
ajcazz

 

[ElijahBaley]

Ajcazz,

Thanks for all your help, much appreciated.

EB