ZyXEL Communications Prestige 661H Series, User Manual

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Prestige 661H/HW Series User’s Guide
Chapter 5 LAN Setup 74
5.2 LAN TCP/IP
The Prestige has built-in DHCP server capability that assigns IP addresses and DNS servers to
systems that support DHCP client capability.
5.2.1 IP Address and Subnet Mask
Similar to the way houses on a street share a common street name, so too do computers on a
LAN share one common network number.
Where you obtain your network number depends on your particular situation. If the ISP or
your network administrator assigns you a block of registered IP addresses, follow their
instructions in selecting the IP addresses and the subnet mask.
If the ISP did not explicitly give you an IP network number, then most likely you have a single
user account and the ISP will assign you a dynamic IP address when the connection is
established. If this is the case, it is recommended that you select a network number from
192.168.0.0 to 192.168.255.0 and you must enable the Network Address Translation (NAT)
feature of the Prestige. The Internet Assigned Number Authority (IANA) reserved this block
of addresses specifically for private use; please do not use any other number unless you are
told otherwise. Let's say you select 192.168.1.0 as the network number; which covers 254
individual addresses, from 192.168.1.1 to 192.168.1.254 (zero and 255 are reserved). In other
words, the first three numbers specify the network number while the last number identifies an
individual computer on that network.
Once you have decided on the network number, pick an IP address that is easy to remember,
for instance, 192.168.1.1, for your Prestige, but make sure that no other device on your
network is using that IP address.
The subnet mask specifies the network number portion of an IP address. Your Prestige will
compute the subnet mask automatically based on the IP address that you entered. You don't
need to change the subnet mask computed by the Prestige unless you are instructed to do
otherwise.
5.2.1.1 Private IP Addresses
Every machine on the Internet must have a unique address. If your networks are isolated from
the Internet, for example, only between your two branch offices, you can assign any IP
addresses to the hosts without problems. However, the Internet Assigned Numbers Authority
(IANA) has reserved the following three blocks of IP addresses specifically for private
networks:
• 10.0.0.0 — 10.255.255.255
• 172.16.0.0 — 172.31.255.255
• 192.168.0.0 — 192.168.255.255