Subnetting Question

Discussion in 'Computer Support' started by meerkat, Jan 25, 2008.

  1. meerkat

    meerkat Guest

    meerkat, Jan 25, 2008
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  2. I just received IP information for a new Internet connection and they
    did not include the Subnet Mask. How can I figure this address? The
    IP is 63.253.x.x
    newworldironman, Jan 25, 2008
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  3. meerkat

    John Doe Guest

    Hey, thanks for the quick response!
    I'm having to pre-configure a router for an office in another city.
    Is there an exact equation that anyone knows of?
    Honestly, I'm afraid to ask the ISP a stupid question but I might just
    have to ask them why they didn't supply the Subnet Mask.
    John Doe, Jan 25, 2008
  4. meerkat

    richard Guest

    Maybe it's not needed.
    richard, Jan 25, 2008
  5. meerkat

    Gaius Baltar Guest covers all the addresses in the network

    Gaius Baltar, Jan 25, 2008
  6. meerkat

    why? Guest

    ..x.x is fairly invalid in most systems.
    Don't ask, tell them they forgot to supply that information. for - subnet calculator

    Depends on if you mean exactly 1 address or a small range.

    At worst case for -
    and how much of that the ISP handed out to other users.

    why?, Jan 26, 2008
  7. meerkat

    Phat Sam Guest

    The MASK determines what computers are in your "local" network.
    Determining the MASK is supposed to be done according to the "class"
    of network your on. Some networks allow for configurations of 256 IP
    addresses, some allow for 65536, and others in between. You can
    create some rather freaky combinations, as the subnet mask is actually
    bit-masked in reality. Eg. suppose you specify:

    Then the only computers that'd be local to yours would be those whose
    IP address is the same as yours on the first 3 sections, with the 4th
    section being either 0,1,4, or 5. This method would allow for in
    theory 4 computers on the local network.... Thus if you did All would be well as long as any of your ISP's has the
    same numbers for the first 3 parts of the IP address.... If not, then
    most ISP's use a subnet mask of Which allows for a range
    of 65536 IP addresses. Thinking about it an ISP with only 256 IP
    addresses would seem rather limited, but your ISP could be a small
    Dial-up with their own equipment (Extremely rare these days as most
    ISP's lease their dial-up lines from other companies....)
    Phat Sam, Jan 27, 2008
  8. meerkat

    why? Guest

    Except where just about everybody uses CIDR. Haven't used "class" to
    subnet anything for a long time.

    250 is freaky, sensible examples and a URL to a subnet tutorial would be
    more useful, better to use .248 or .252.

    250 isn't contiguous bits, 11111010 and that's mentioned in the RFC as
    not illegal however real life / pratical support and the messy
    addressing means it's not used in and to be avoided.
    0, 1, 4 and 5 is also odd, from your example.

    If you are going to try and explain something about subnetting avoid the
    freaky examples.
    Why use section in place of the common usage octet?


    why?, Jan 28, 2008
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