ZyXEL Communications MAX318M2W, User Manual

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Chapter 7 Network Settings
MAX318M2W User’s Guide
86
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; 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 WiMAX Device supports the IPCP DNS server extensions through
the DNS proxy feature.
If the Primary and Secondary DNS Server fields are not specified, for instance,
left as 0.0.0.0, the WiMAX Device tells the DHCP clients that it itself is the DNS
server. When a computer sends a DNS query to the WiMAX Device, the WiMAX
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. This way, the WiMAX Device can pass the
DNS servers to the computers and the computers can query the DNS server
directly without the WiMAX Device’s intervention.
Wireless Basics
“Wireless” is essentially radio communication. In the same way that walkie-talkie
radios send and receive information over the airwaves, wireless networking
devices exchange information with one another. A wireless networking device is
just like a radio that lets your computer exchange information with radios
attached to other computers. Like walkie-talkies, most wireless networking
devices operate at radio frequency bands that are open to the public and do not
require a license to use. However, wireless networking is different from that of
most traditional radio communications in that there a number of wireless
networking standards available with different methods of data encryption.