ZyXEL Communications 5 Series User Manual

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ZyWALL 5/35/70 Series User’s Guide
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DNS Screens
26.1  Overview
This chapter shows you how to configure the DNS screens.
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 ZyWALL uses a system DNS server (in 
the order you specify in the DNS System screen) to resolve domain names, for example, VPN, 
DDNS and the time server.
26.1.1  What You Can Do in the DNS Screens
• Use the System screen (
) to configure the ZyWALL to use a 
DNS server to resolve domain names for ZyWALL system features like VPN, DDNS and 
the time server.
• Use the Add Address Record screen (
) to add an address 
record.
• Use the Insert Name Server Record screen (
) to insert a 
name server record.
• Use the Cache screen (
) to configure the ZyWALL’s DNS 
caching settings.
• Use the DHCP screen (
information that the ZyWALL sends to its LAN, DMZ or WLAN DHCP clients.
• Use the DDNS screen (
) to change your ZyWALL’s DDNS 
(Dynamic DNS) settings.
26.1.2  What You Need To Know About DNS
DNS Server Address Assignment
The ZyWALL can get the DNS server addresses in the following ways.
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, manually enter them in 
the DNS server fields.
If your ISP dynamically assigns the DNS server IP addresses (along with the ZyWALL’s 
WAN IP address), set the DNS server fields to get the DNS server address from the ISP.