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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 ADSL Router 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 ADSL Router tells the DHCP clients that it itself is the
DNS server. When a computer sends a DNS query to the ADSL Router, the ADSL
Router 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 ADSL Router
can pass the DNS servers to the computers and the computers can query the DNS
server directly without the ADSL Router’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 ADSL Router acts as a DNS proxy when this field is blank.
4.4 LAN TCP/IP
The ADSL Router has built-in DHCP server capability that assigns IP addresses and
DNS servers to systems that support DHCP client capability.
