ZyXEL Communications ZYWALL10 - Manual (Page 49)

ZyWALL 10 Internet Security Gateway
Internet Access 3-1
Chapter 3
Internet Access
This chapter shows you how to configure the LAN as well as the WAN of your ZyWALL for Internet
access.
3.1 TCP/IP and DHCP for LAN
The ZyWALL has built-in DHCP server capability that assigns IP addresses and DNS servers to systems that
support DHCP client capability.
3.1.1 Factory LAN Defaults
The LAN parameters of the ZyWALL are preset in the factory with the following values:
1. IP address of 192.168.1.1 with subnet mask of 255.255.255.0 (24 bits)
2. DHCP server enabled with 32 client IP addresses starting from 192.168.1.33.
These parameters should work for the majority of installations. If your ISP gives you an explicit DNS server
address(es), skip ahead to section 3.2 to see how to enter the DNS server address(es).
3.1.2 DHCP Configuration
DHCP (Dynamic Host Configuration Protocol, RFC 2131 and RFC 2132) allows the individual clients to
obtain the TCP/IP configuration at start-up from a server. You can configure the ZyWALL as a DHCP server
or disable it. When configured as a server, the ZyWALL provides the TCP/IP configuration for the clients. If
set to None, DHCP service will be disabled and you must have another DHCP sever on your LAN, or else
the workstation must be manually configured.
IP Pool Setup
The ZyWALL is pre-configured with a pool of 32 IP addresses starting from 192.168.1.33 to 192.168.1.64.
This configuration leaves 31 IP addresses (excluding the ZyWALL itself) in the lower range for other server
machines, e.g., server for mail, FTP, telnet, web, etc., that you may have.
DNS Server Address
DNS (Domain Name System) is to map a domain name to its corresponding IP address and vice versa, e.g.,
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 machine before you can access it.
There are two ways that an ISP disseminates the DNS server addresses. The first is for an ISP to tell a
customer the DNS server addresses, usually in the form of an information sheet, when you sign up. If your
ISP does give you the DNS server addresses, enter them in the DNS Server fields in DHCP Setup. The
second is to leave this field blank, i.e., 0.0.0.0 — in this case the ZyWALL acts as a DNS proxy.