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Subnetting Question

Discussion in 'General Cisco Certifications' started by Apoc220, Feb 25, 2012.

  1. Apoc220

    Apoc220 Byte Poster

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    Hey guys,

    So I have been doing some practice with subnetting and have a question regarding VLSM. Let's say you have an IP address of 192.168.1.1. I know you would normally have to do the subnet mask of 255.255.255.0 since it's a class C. However, with VLSM would it be a best practice to use a subnet below /24? For example, would it be alright to use a subnet mask of 255.255.0.0 with this class C address? I ask because I modified my wireless router (prior to my subnetting practice) and assigned it a subnet of 255.255.0.0 with the hopes of using the third octet to make different subnets for some labbing that I was doing with server 2008. Looking back on it I should have just done a 255.255.255.128 subnet mask thus giving me two subnets which is what I was looking for anyway. Anyway, it was working fine with the 255.255.0.0 subnet mask, but I just wanted to make sure that this was a best practice. Thanks, guys!
     
    Certifications: MCDST
    WIP: 70-680
  2. keconnect sparky

    keconnect sparky Nibble Poster

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    It always best to use the subnet mask that is most fitting/relevant/correct

    As otherwise you could have issues with other networks/ACLs, or depending or where you are entering these networks (say into a routing protocol) you could be advertising networks you do not have
     
    Certifications: MCP, CCENT, CCNA, CCNA-S
    WIP: CCNP (ROUTE)

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