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#1 polska03   User is offline

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ccna skills exam subnetting

Posted 07 November 2010 - 03:41 PM

I had a ccna skills exam on packet tracer where the scernerio looked something like this. It had 2 networks with one router joining those 2 networks and a pc and switch in each network. Kind of like this pc1--->switch1--->router1---->switch2---->pc2. The object of this was that you are given the network address of 172.16.1.0/24. network 1 has to have 30 hosts and network 2 has to have 10 hosts, and to have no wasted address space. So what I did was take the ip address and borrow 3 bit for a subnet of /27, This way I was got 30 hosts for both networks. So I had my two networks 172.16.1.0 and 172.16.1.128 which I used and I configured all the routers and switches. Everything ran great and was able to ping the other network. After I got a very low mark and was wondering if it had something to do with the fact I have 30 hosts for both networks, while 1 network needs 30 and the other needs only 10 and it said we should not waste address space. I was wondering if I should use vlsm and if so if someone could show the answer with vlsm.

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Replies To: ccna skills exam subnetting

#2 AlbuquerqueApache   User is offline

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Re: ccna skills exam subnetting

Posted 08 November 2010 - 06:19 AM

View Postpolska03, on 07 November 2010 - 02:41 PM, said:

I had a ccna skills exam on packet tracer where the scernerio looked something like this. It had 2 networks with one router joining those 2 networks and a pc and switch in each network. Kind of like this pc1--->switch1--->router1---->switch2---->pc2. The object of this was that you are given the network address of 172.16.1.0/24. network 1 has to have 30 hosts and network 2 has to have 10 hosts, and to have no wasted address space. So what I did was take the ip address and borrow 3 bit for a subnet of /27, This way I was got 30 hosts for both networks. So I had my two networks 172.16.1.0 and 172.16.1.128 which I used and I configured all the routers and switches. Everything ran great and was able to ping the other network. After I got a very low mark and was wondering if it had something to do with the fact I have 30 hosts for both networks, while 1 network needs 30 and the other needs only 10 and it said we should not waste address space. I was wondering if I should use vlsm and if so if someone could show the answer with vlsm.


I guess the VLSM (variable length subnetting) is what throws me. I tired to compute a subnet that would meet these specs and network 2 can only have 6 or 13 hosts, not 10. I probably need to read more into VLSM because I think Im just using traditionally subnetting using 2^N-2 networks.
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