Private Ip

Private IP: In order to differentiate between private IP and public IP few keys items needs to be taken care of: read RFC 1918.

 Private Address Space

    The Internet Assigned Numbers Authority (IANA) has reserved the
    following three blocks of the IP address space for private internets:

      10.0.0.0        -   10.255.255.255  (10/8 prefix)
      172.16.0.0      -   172.31.255.255  (172.16/12 prefix)
      192.168.0.0     -   192.168.255.255 (192.168/16 prefix)

    We will refer to the first block as "24-bit block", the second as
    "20-bit block", and to the third as "16-bit" block. Note that (in
    pre-CIDR notation) the first block is nothing but a single class A
    network number, while the second block is a set of 16 contiguous
    class B network numbers, and third block is a set of 256 contiguous
    class C network numbers.

    An enterprise that decides to use IP addresses out of the address
    space defined in this document can do so without any coordination
    with IANA or an Internet registry. The address space can thus be used
    by many enterprises. Addresses within this private address space will
    only be unique within the enterprise, or the set of enterprises which
    choose to cooperate over this space so they may communicate with each
    other in their own private internet.

    As before, any enterprise that needs globally unique address space is
    required to obtain such addresses from an Internet registry. An
    enterprise that requests IP addresses for its external connectivity
    will never be assigned addresses from the blocks defined above.

    In order to use private address space, an enterprise needs to
    determine which hosts do not need to have network layer connectivity
    outside the enterprise in the foreseeable future and thus could be
    classified as private. Such hosts will use the private address space
    defined above.  Private hosts can communicate with all other hosts
    inside the enterprise, both public and private. However, they cannot
    have IP connectivity to any host outside of the enterprise. While not
    having external (outside of the enterprise) IP connectivity private
    hosts can still have access to external services via mediating
    gateways (e.g., application layer gateways).

    All other hosts will be public and will use globally unique address
    space assigned by an Internet Registry. Public hosts can communicate
    with other hosts inside the enterprise both public and private and
    can have IP connectivity to public hosts outside the enterprise.
    Public hosts do not have connectivity to private hosts of other
    enterprises.