Dhcp Setup; Dns Server Addresses; Lan Tcp/Ip - ZyXEL Communications VMG Series User Manual

10.9.1 DHCP Setup

DHCP (Dynamic Host Configuration Protocol, RFC 2131 and RFC 2132) allows individual clients to obtain
TCP/IP configuration at start-up from a server. You can configure the Zyxel Device as a DHCP server or
disable it. When configured as a server, the Zyxel Device provides the TCP/IP configuration for the
clients. If you turn DHCP service off, you must have another DHCP server on your LAN, or else the
computer must be manually configured.
IP Pool Setup
The Zyxel Device is pre-configured with a pool of IP addresses for the DHCP clients (DHCP Pool). See the
product specifications in the appendices. Do not assign static IP addresses from the DHCP pool to your
LAN computers.

10.9.2 DNS Server Addresses

DNS (Domain Name System) maps 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. 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 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.
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.

10.9.3 LAN TCP/IP

The Zyxel Device 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
Chapter 10 Home Networking
VMG/EMG/AM/DM/GM Series User's Guide
258