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-   -   Subnetting a Class A network ID (https://www.askmehelpdesk.com/showthread.php?t=190791)

  • Mar 3, 2008, 08:20 PM
    davidlfranklin
    Subnetting a Class A network ID
    I am a trying to understand Subnetting:

    Given an IP Network Adress:
    10.0.0.0 Mask 255.0.0.0
    Borrowing 2 bits from Octet 2
    I get subnetwork 10.64.0.0
    IP Host Range as 10.64.0.1 to 10.127.255.254

    Question:
    After above reaches 10.64.0.254 does it go to 10.64.1.254 Then 10.64.2.1 up to 10.64.255.254
    Then 10.65.0.1 up to 10.65.1.1... and so on up to 10.127 network?

    Thank you
    David Franklin
  • Mar 4, 2008, 06:48 AM
    TechEmperor
    That's exactly correct. 10.64.0.1-254, then 10.64.1.1-254, all the way to 10.64.255.254, then 10.65.0.1-254 and on and on and on up to 10.127.255.254.
  • Mar 4, 2008, 09:22 AM
    chuckhole
    This is a must see site for you to understand the 32-bit binary TCP/IP address of IPv4.

    Learn To Subnet:  A Free, Lecture-Based Presentation on IP Addressing and Subnetting

    The tutorials will guide you through the conversions of the binary to hex addressing and will then show you how to subnet (cut the pie into pieces) your network. You can get a better understanding of what is a network and host ID and apply this to LAN/WAN technologies. Kudos to who ever put this together.
  • Mar 5, 2008, 05:00 PM
    cajalat
    Quote:

    Originally Posted by davidlfranklin
    I am a trying to understand Subnetting:

    Given an IP Network Adress:
    10.0.0.0 Mask 255.0.0.0
    Borrowing 2 bits from Octet 2
    I get subnetwork 10.64.0.0
    IP Host Range as 10.64.0.1 to 10.127.255.254

    Question:
    after above reaches 10.64.0.254 does it go to 10.64.1.254 Then 10.64.2.1 up to 10.64.255.254
    Then 10.65.0.1 up to 10.65.1.1...and so on up to 10.127 network?

    Thank you
    David Franklin

    Using your numbers as an example, when you borrow 2 bits, you will have a network 10.0.0.0 with a mask of 255.192.0.0. This gives you a range from:

    10.0.0.0 - 10.63.255.255

    The above is considered ONE subnet and ALL IP's within that range are usable and assignable to hosts starting with 10.0.0.1 and ending with 10.63.255.254. 10.0.0.0 is the network address and 10.63.255.255 is the network broadcast address. All other IPs in between such as 10.50.0.0, 10.30.255.255 are valid IP's for hosts. So you can have a host with 10.20.255.255 with a mask of 255.192.0.0 and that would be valid.

    So again using your example you end up with 4 Subnets as follows:


    10.0.0.0/255.192.0.0 = 10.0.0.0 - 10.63.255.255 (usable 10.0.0.1 - 10.63.255.254)
    10.64.0.0/255.192.0.0 = 10.64.0.0 - 10.127.255.255 (usable 10.64.0.1 - 10.127.255.254)
    10.128.0.0/255.192.0.0 = 10.128.0.0 - 10.191.255.255 (usable 10.128.0.1 - 10.191.255.254)
    10.192.0.0/255.192.0.0 = 10.192.0.0 - 10.255.255.255 (usable 10.192.0.1 - 10.255.255.254)

    Again within the usable range anything ending with .0 or .255 are valid and usable IPs.

    Casey

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