Lan Tcp/Ip - ZyXEL Communications AMG1001-T Series User Manual

Chapter 8 LAN Setup
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 Primary and
Secondary DNS Server fields.
• 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 AMG1001-T/
AMG1011-T supports the IPCP DNS server extensions through the DNS proxy feature.
If the DHCP is set to Relay, the AMG1001-T/AMG1011-T tells the DHCP clients that it itself is the
DNS server. When a computer sends a DNS query to the AMG1001-T/AMG1011-T, the AMG1001-
T/AMG1011-T 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.

8.3.4 LAN TCP/IP

The AMG1001-T/AMG1011-T has built-in DHCP server capability that assigns IP addresses and DNS
servers to systems that support DHCP client capability.
IP Address and Subnet Mask
Similar to the way houses on a street share a common street name, so too do computers on a LAN
share one common network number.
Where you obtain your network number depends on your particular situation. If the ISP or your
network administrator assigns you a block of registered IP addresses, follow their instructions in
selecting the IP addresses and the subnet mask.
If the ISP did not explicitly give you an IP network number, then most likely you have a single user
account and the ISP will assign you a dynamic IP address when the connection is established. If this
is the case, it is recommended that you select a network number from 192.168.0.0 to
192.168.255.0 and you must enable the Network Address Translation (NAT) feature of the
AMG1001-T/AMG1011-T. The Internet Assigned Number Authority (IANA) reserved this block of
addresses specifically for private use; please do not use any other number unless you are told
otherwise. Let's say you select 192.168.1.0 as the network number; which covers 254 individual
addresses, from 192.168.1.1 to 192.168.1.254 (zero and 255 are reserved). In other words, the
first three numbers specify the network number while the last number identifies an individual
computer on that network.
Once you have decided on the network number, pick an IP address that is easy to remember, for
instance, 192.168.1.1, for your AMG1001-T/AMG1011-T, but make sure that no other device on
your network is using that IP address.
The subnet mask specifies the network number portion of an IP address. Your AMG1001-T/
AMG1011-T will compute the subnet mask automatically based on the IP address that you entered.
You don't need to change the subnet mask computed by the AMG1001-T/AMG1011-T unless you
are instructed to do otherwise.
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AMG1001-T/AMG1011-T Series User's Guide