ZyXEL Communications MAX-200HW2, User Manual

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Chapter 9 LAN
MAX-200HW2 Series User ’ s Guide
120
9.1.2 DHCP Setup
DHCP (Dynamic Host Configuration Protocol, RFC 2131 and RFC 2132) allows individual
clients to obtain TCP/IP configuration at start-up from a server. You can configure the ZyXEL
Device as a DHCP server or disable it. When configured as a server, the ZyXEL Device
provides the TCP/IP configuration for the clients. If DHCP service is disabled, you must have
another DHCP server on your LAN, or else each computer must be manually configured.
The ZyXEL Device is pre-configured with a pool of IP addresses for the DHCP clients (DHCP
Pool). See the product specifications in the appendices. Do not assign static IP addresses from
the DHCP pool to your LAN computers.
These parameters should work for the majority of installations. If your ISP gives you explicit
DNS server address(es), see Section 9.2.2 on page 122 .
9.1.3 LAN TCP/IP
The ZyXEL Device has built-in DHCP server capability that assigns IP addresses and DNS
servers to systems that support DHCP client capability.
The LAN parameters of the ZyXEL Device are preset in the factory with the following values:
• IP address of 192.168.1.1 with subnet mask of 255.255.255.0 (24 bits)
• 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 explicit
DNS server address(es), see Section 9.2.2 on page 122 .
9.1.4 DNS Server Address
DNS (Domain Name System) is for mapping a domain name to its corresponding IP address
and vice versa. The DNS server is extremely important because without it, you must know the
IP address of a machine before you can access it. The DNS server addresses that you enter in
the DHCP setup are passed to the client machines along with the assigned IP address and
subnet mask.
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
s/he signs up. If your ISP gives you the DNS server addresses, enter them in the DNS Server
fields in DHCP Setup , otherwise, leave them blank.
Some ISPs choose to pass the DNS servers using the DNS server extensions of PPP IPCP (IP
Control Protocol) after the connection is up. If your ISP did not give you explicit DNS servers,
chances are the DNS servers are conveyed through IPCP negotiation. The ZyXEL Device
supports the IPCP DNS server extensions through the DNS proxy feature.
If the
Primary and Secondary DNS Server fields in the LAN Setup screen are not specified,
for instance, left as 0.0.0.0, the ZyXEL Device tells the DHCP clients that it itself is the DNS
server. When a computer sends a DNS query to the ZyXEL Device, the ZyXEL Device
forwards the query to the real DNS server learned through IPCP and relays the response back
to the computer.