Dhcp Setup; Dns Server Addresses - ZyXEL Communications P-792H User Manual

Chapter 7 LAN Setup

7.6.2 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 P-792H v2 as a DHCP server or disable it. When configured as a
server, the P-792H v2 provides the TCP/IP 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.
IP Pool Setup
The P-792H v2 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.

7.6.3 DNS Server Addresses

DNS (Domain Name System) maps 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. The DNS
server addresses you enter when you set up DHCP 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 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.
• Some ISPs choose to disseminate the DNS server addresses using the DNS
server extensions of 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 P-792H v2 supports the IPCP DNS
server extensions through the DNS proxy feature.
If the DNS Server fields in the DHCP Setup screen are set to DNS Relay, the
P-792H v2 tells the DHCP clients that it itself is the DNS server. When a
computer sends a DNS query to the P-792H v2, the P-792H v2 acts as a DNS
proxy and 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.
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P-792H v2 User's Guide