Ip Address And Subnet Mask; Dns Server Address Assignment - ZyXEL Communications Internet Security Gateway ZyWALL 2 Series User Manual

Regardless of your particular situation, do not create an arbitrary IP address;
always follow the guidelines above. For more information on address assignment,
please refer to RFC 1597, Address Allocation for Private Internets and RFC 1466,

3.4.2 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 ZyWALL. 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 ZyWALL, 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 ZyWALL 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 ZyWALL unless you are instructed to do otherwise.

3.4.3 DNS Server Address Assignment

Use DNS (Domain Name System) to map a domain name to its corresponding IP address and vice versa, for
instance, the IP address of www.zyxel.com is 204.217.0.2. The DNS server is extremely important because
without it, you must know the IP address of a computer before you can access it.
The ZyWALL can get the DNS server addresses in the following ways.
1. The ISP tells you the DNS server addresses, usually in the form of an information sheet, when you sign
up. If your ISP gives you DNS server addresses, enter them in the DNS Server fields in DHCP Setup.
2. If the ISP did not give you DNS server information, leave the DNS Server fields in DHCP Setup set to
0.0.0.0 for the ISP to dynamically assign the DNS server IP addresses.
Wizard Setup
Guidelines for Management of IP Address Space.
ZyWALL 2 Series User's Guide
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