ZyXEL Communications Prestige 792H, User Manual

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Prestige 792H User’s Guide
4-2 LAN Setup
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 ISP’s 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 Prestige supports the IPCP DNS server extensions
through the DNS proxy feature.
If the Primary and Secondary DNS Server fields in DHCP Setup are not specified, for instance, left as
0.0.0.0, the Prestige tells the DHCP clients that it itself is the DNS server. When a computer sends a DNS
query to the Prestige, the Prestige forwards the query to the real DNS server learned through IPCP and relays
the response back to the computer.
Please note that DNS proxy works only when the ISP uses the IPCP DNS server extensions. It does not
mean you can leave the DNS servers out of the DHCP setup under all circumstances. If your ISP gives you
explicit DNS servers, make sure that you enter their IP addresses in the
DHCP Setup menu. This way, the
Prestige can pass the DNS servers to the computers and the computers can query the DNS server directly
without the Prestige’s intervention.
4.3 DNS Server Address Assignment
Use DNS (Domain Name System) to map 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 computer before
you can access it.
There are two ways that an ISP disseminates the DNS server addresses.
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. Leave the DNS Server fields in DHCP Setup blank (for example 0.0.0.0). The Prestige acts as a DNS
proxy when this field is blank.
4.4 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.