User's Manual

IP Addresses
User Guide 5
IP Addresses
IP addresses are like street addresses—when you want to send some
information to someone, you must first know his or her address.
Similarly, when a computer connected to the Internet needs to send
data to another computer, it must first know its IP address.
Each computer on the Internet has its own unique IP address. An IP
address consists of four sets of numbers separated by decimal
points. Examples of IP addresses are:
• 192.168.0.11
• 10.1.20.18
• 208.15.15.15
A firewall device such as the Firebox® X Edge is also a computer and
therefore has its own IP address.
Network addressing
Your ISP assigns IP addresses, which are a requirement to connect to
the Internet. The assignment of IP addresses is
dynamic or static .
Static IP addressing occurs when an ISP permanently assigns one or
more IP addresses for each user. These addresses do not change over
time. However, if a static address is assigned but not in use, it is
effectively wasted. Because ISPs have a limited number of addresses
allocated to them, they sometimes need to make more efficient use
of their addresses.
Dynamic IP addressing allows the ISP to use their address space
more efficiently. Using dynamic IP addressing, the IP addresses of
individual user computers may change over time. If a dynamic
address is not in use (the user is not connected to the network), it
can be automatically reassigned to another computer as needed.
Your ISP can tell you how their system assigns IP addresses.
About DHCP
Most ISPs make dynamic IP address assignments through (Dynamic
Host Configuration Protocol (DHCP). When a computer connects to
the network, a DHCP server at the ISP assigns that computer an IP
address. The manual assignment of IP addresses is not necessary
when using DHCP.