Chapter 26 Dns; Dns Server Address Assignment; Dns Servers - ZyXEL Communications Internet Security Appliance ZyWALL5UTM 4.0 User Manual

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This chapter shows you how to configure the DNS screens.

26.1 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. 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.

The ZyWALL can get the DNS server addresses in the following ways.

1 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.

2 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.

3 You can manually enter the IP addresses of other DNS servers. These servers can be

public or private. A DNS server could even be behind a remote IPSec router (see

26.5.1 on page

There are three places where you can configure DNS setup on the ZyWALL.

1 Use the DNS 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.

2 Use the DNS DHCP screen to configure the DNS server information that the ZyWALL

sends to the DHCP client devices on the LAN, DMZ or WLAN.

3 Use the REMOTE MGMT DNS screen to configure the ZyWALL (in router mode) to

accept or discard DNS queries.

Chapter 26 DNS

ZyWALL 5/35/70 Series User's Guide