Dns Server Address; Dns Server Address Assignment - ZyXEL Communications P-660R-F1 series User Manual

Chapter 5 LAN Setup
configuration for the clients. If you turn DHCP service off, you must have another DHCP server on
your LAN, or else the computer must be manually configured.
5.1.2.1 IP Pool Setup
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.

5.1.3 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 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 ZyXEL Device supports
the IPCP DNS server extensions through the DNS proxy feature.
If the Primary and Secondary DNS Server fields in the DHCP 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.
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
screen. This way, the ZyXEL Device can pass the DNS servers to the computers and the computers
can query the DNS server directly without the ZyXEL Device's intervention.

5.1.4 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.
• 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
the DHCP Setup screen.
• The ZyXEL Device acts as a DNS proxy when the Primary and Secondary DNS Server fields
are left as 0.0.0.0 in the DHCP Setup screen.
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P-660R-F1 Series User's Guide