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  1. #1
    Join Date
    Dec 2010
    Posts
    11

    Default last valid host on subnetwork

    Hello, I and new to subnetting and currently trying to prepare for the ccent exam. I have the Todd Lammle Study Guide.

    Question: can any one explain: What is the last valid host on the subnetwork 172.25.192.0/22, Thanks

  2. #2
    Join Date
    Aug 2009
    Location
    California, US
    Posts
    115

    Default

    A /22 means that we want to subnet the 3rd octet. A /22 also means we will use a block of 4 in the 3rd octet.

    the network address is 172.25.192.0
    the first host address is 172.25.192.1
    the last host address is 172.25.195.254
    the broadcast address is 172.25.195.255

    the next network would start at 172.25.196.0. Remember that the /22 means that we are using blocks of 4 in the 3rd octet.

  3. #3
    Join Date
    Jun 2011
    Posts
    59

    Default what does subnetwork mean?

    When you guys mean subnetwork is that the subnet or the actual host ip address of the broadcast address?

  4. #4
    Join Date
    Nov 2008
    Location
    Birmingham, UK
    Posts
    1,447

    Default

    A subnetwork, or subnet, is the range of IP addresses that are valid for the network IP/subnet mask chosen. It's referred to by the network address IP and either its netmask or its CIDR notation.

    e.g

    192.168.2.0 255.255.254.0 or 192.168.2.0/23.
    CCNP R&S, CCNA DC
    Currently studying: CCIE R&S, CCNP Data Centre
    Follow my CCIE progress with study notes on my blog: http://beyondccna.blogspot.co.uk/

  5. #5
    Join Date
    Jun 2011
    Posts
    59

    Default

    When I work out his question, it shows that the subnetwork address is the network address.

    What is the subnetwork number of a host with an IP address of 172.16.66.0/21?

    A. 172.16.36.0
    B. 172.16.48.0
    C. 172.16.64.0
    D. 172.16.0.0

    /21 is a block 8

    172.16.8.0 - 172.16.15.255
    172.16.16.0 - 172.16.23.255
    172.16.24.0 - 172.16.31.255
    ...
    172.16.56.0 - 172.16.63.255
    172.16.64.0 - 172.16.71.255

    The answer to the question is 172.16.64.0

    Would this be correct, as the subnetwork is the network ip address?

  6. #6
    Join Date
    Nov 2008
    Location
    Birmingham, UK
    Posts
    1,447

    Default

    That is correct
    CCNP R&S, CCNA DC
    Currently studying: CCIE R&S, CCNP Data Centre
    Follow my CCIE progress with study notes on my blog: http://beyondccna.blogspot.co.uk/

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