ZyXEL Communications 3.1 User Manual

Page of 386
 Chapter 37 System
ZyWALL (ZLD) CLI Reference Guide
283
37.6  DNS Overview 
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. 
37.6.1  Domain Zone Forwarder 
A domain zone forwarder contains a DNS server’s IP address. The ZyWALL can query the DNS 
server to resolve domain zones for features like VPN, DDNS and the time server. A domain zone is a 
fully qualified domain name without the host. For example, zyxel.com.tw is the domain zone for the 
www.zyxel.com.tw fully qualified domain name. 
37.6.2  DNS Commands
The following table identifies the values required for many of these commands. Other input values 
are discussed with the corresponding commands.
The following table describes the commands available for DNS. You must use the 
configure 
terminal
 command to enter the configuration mode before you can use these commands.
 
Table 168   
Input Values for General DNS Commands
LABEL
DESCRIPTION
address_object
The name of the IP address (group) object. You may use 1-31 alphanumeric characters, 
underscores(
_
), or dashes (-), but the first character cannot be a number. This value is 
case-sensitive. 
interface_name
The name of the interface.
Ethernet interface: For the ZyWALL USG 300 and above, use gexx = 1 - N, where N 
equals the highest numbered Ethernet interface for your ZyWALL model.
The ZyWALL USG 200 and lower models use a name such as wan1, wan2, opt, lan1, 
ext-wlan, or dmz.
virtual interface on top of Ethernet interface: add a colon (:) and the number of the 
virtual interface. For example: gex:yx = 1 - N, y = 1 - 4
VLAN interface: vlanxx = 0 - 4094
virtual interface on top of VLAN interface: vlanx:yx = 0 - 4094, y = 1 - 12
bridge interface: brxx = 0 - N, where N depends on the number of bridge interfaces your 
ZyWALL model supports.
virtual interface on top of bridge interface: brx:yx = the number of the bridge interface, 
y = 1 - 4
PPPoE/PPTP interface: pppxx = 0 - N, where N depends on the number of PPPoE/PPTP 
interfaces your ZyWALL model supports.
Table 169   
Command Summary: DNS
COMMAND
DESCRIPTION
[no] ip dns server a-record fqdn w.x.y.z
Sets an A record that specifies the mapping of a fully qualified 
domain name (FQDN) to an IP address. The 
no
 command deletes 
an A record.
ip dns server -flush
Clears the DNS .