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

11 Configuring IP
11.1.2

Private vs. Public Addresses

Introduction
In this subsection
Private IP addresses
Using private
addresses
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Private PC/workstation(s) do not require access to
PC/workstation(s) in other enterprises, or to the Internet. Therefore
it is sufficient for the PC/workstation 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.
This subsection covers the following topics:
Private IP Addresses
"
Using Private Addresses
"
Private PC(s) accessing Public Services
"
Private IP Address Classes
"
Public IP Addresses
"
Using Public 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".
In principle if an IP address is assigned to a PC/workstation and the
connectivity is limited to intra enterprise communication only, the IP
address can 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.
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