ZyXEL Communications Corporation OX253P Manual De Usuario
Chapter 6 The LAN Configuration Screens
OX253P User’s Guide
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6.6.3 LAN TCP/IP
The OX253P has built-in DHCP server capability that assigns IP addresses and
DNS servers to systems that support DHCP client capability.
DNS servers to systems that support DHCP client capability.
The LAN parameters of the OX253P are preset in the factory with the following
values:
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.
• 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
you explicit DNS server address(es), see
Section 6.3 on page 56
.
6.6.4 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.
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.
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 OX253P supports the IPCP DNS server extensions through the
DNS proxy feature.
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 OX253P 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 OX253P tells the DHCP clients that
it itself is the DNS server. When a computer sends a DNS query to the OX253P,
the OX253P forwards the query to the real DNS server learned through IPCP and
relays the response back to the computer.
not specified, for instance, left as 0.0.0.0, the OX253P tells the DHCP clients that
it itself is the DNS server. When a computer sends a DNS query to the OX253P,
the OX253P 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 LAN Setup screen. This way, the
OX253P can pass the DNS servers to the computers and the computers can query
the DNS server directly without the OX253P’s intervention.
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 LAN Setup screen. This way, the
OX253P can pass the DNS servers to the computers and the computers can query
the DNS server directly without the OX253P’s intervention.