Private Vs. Public Addresses - Alcatel Speed Touch Wireless User Manual

11 Networking Services - IP
11.1.2

Private vs. Public Addresses

Introduction
Private PC(s) do not require access to PC(s) in other enterprises, or
to the Internet. Therefore it is sufficient for the PC to have an IP
address that is unique within the enterprise but may be ambiguous
between enterprises and on the Internet.
On the other hand there is also a need for Internet wide" unique
IP addresses to allow web servers to be constantly online.
The first set of addresses are called Private IP addresses; the
second set Public IP addresses.
Private IP addresses
In the examples throughout this document Private IP addresses are
used for local IP configurations.
Private IP addresses are defined in RFC1918 Address Allocation
for Private Internets". This RFC is categorized as "Best Current
Practice".
Using private
In principle if an IP address is assigned to a PC and the connectivity
is limited to intra enterprise communication only, the IP address can
addresses
be assumed to be privately held.
The limitation however is that communication between enterprises
and connection to the Internet itself via those private IP addressed
PCs is not possible, and even not allowed.
Private PC(s) accessing
Via mediating gateways (e.g. the STWireless) private PC(s) can
still have access to external services, e.g. the Internet.
public services
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