Tcp/Ip - ZyXEL Communications P-2612HW-F1 User Manual

• 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 ZyXEL Device 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
ZyXEL Device tells the DHCP clients that it itself is the DNS server. When a
computer sends a DNS query to the ZyXEL Device, the ZyXEL Device 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.

7.5.4 TCP/IP

The ZyXEL Device has built-in DHCP server capability that assigns IP addresses
and DNS servers to systems on the LAN 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 ZyXEL Device. 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.
P-2612HW-F1 User's Guide
Chapter 7 LAN Setup
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