Chapter 21 DNS
ZyWALL 2WG User’s Guide
433
The following table describes the labels in this screen.
21.7 DNS Cache
DNS cache is the temporary storage area where a router stores responses from DNS servers.
When the ZyWALL receives a positive or negative response for a DNS query, it records the
response in the DNS cache. A positive response means that the ZyWALL received the IP
address for a domain name that it checked with a DNS server within the five second DNS
timeout period. A negative response means that the ZyWALL did not receive a response for a
query it sent to a DNS server within the five second DNS timeout period.
When the ZyWALL receives DNS queries, it compares them against the DNS cache before
querying a DNS server. If the DNS query matches a positive entry, the ZyWALL responses
with the IP address from the entry. If the DNS query matches a negative entry, the ZyWALL
replies that the DNS query failed.
21.8 Configure DNS Cache
To configure your ZyWALL’s DNS caching, click
ADVANCED
>
DNS
>
Cache
. The screen
appears as shown.
Table 139
ADVANCED > DNS > Insert (Name Server Record)
LABEL
DESCRIPTION
Domain Zone
This field is optional.
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. For example, whenever the ZyWALL receives needs to resolve a
zyxel.com.tw domain name, it can send a query to the recorded name server IP
address.
Leave this field blank if all domain zones are served by the specified DNS server(s).
DNS Server
Select the
DNS Server(s) from ISP
radio button if your ISP dynamically assigns
DNS server information. You also need to select an interface through which the ISP
provides the DNS server IP address(es). The interface should be activated and set
as a DHCP client.The fields below display the (read-only) DNS server IP
address(es) that the ISP assigns.
N/A
displays for any DNS server IP address fields
for which the ISP does not assign an IP address.
N/A
displays for all of the DNS
server IP address fields if the ZyWALL has a fixed WAN IP address.
Select
Public DNS Server
if you have the IP address of a DNS server. The IP
address must be public or a private address on your local LAN. Enter the DNS
server's IP address in the field to the right.
Public DNS Server
entries with the IP address set to 0.0.0.0 are not allowed.
Select
Private DNS Server
if the DNS server has a private IP address and is located
behind a VPN peer. Enter the DNS server's IP address in the field to the right.
With a private DNS server, you must also configure the first DNS server entry for the
LAN, DMZ and/or WLAN in the
DNS DHCP
screen to use
DNS Relay
.
You must also configure a VPN rule since the ZyWALL uses a VPN tunnel when it
relays DNS queries to the private DNS server. The rule must include the LAN IP
address of the ZyWALL as a local IP address and the IP address of the DNS server
as a remote IP address.
Private DNS Server
entries with the IP address set to 0.0.0.0 are not allowed.
Apply
Click
Apply
to save your changes back to the ZyWALL.
Cancel
Click
Cancel
to exit this screen without saving.
Summary of Contents for ZYWALL 2 WG
Page 2: ......
Page 8: ...Safety Warnings ZyWALL 2WG User s Guide 8 ...
Page 42: ...List of Figures ZyWALL 2WG User s Guide 42 ...
Page 50: ...List of Tables ZyWALL 2WG User s Guide 50 ...
Page 52: ...52 ...
Page 80: ...Chapter 2 Introducing the Web Configurator ZyWALL 2WG User s Guide 80 ...
Page 100: ...Chapter 3 Wizard Setup ZyWALL 2WG User s Guide 100 ...
Page 140: ...Chapter 4 Tutorial ZyWALL 2WG User s Guide 140 ...
Page 146: ...146 ...
Page 158: ...Chapter 6 LAN Screens ZyWALL 2WG User s Guide 158 ...
Page 171: ...Chapter 8 WAN Screens ZyWALL 2WG User s Guide 171 Figure 108 NETWORK WAN General ...
Page 200: ...Chapter 8 WAN Screens ZyWALL 2WG User s Guide 200 ...
Page 238: ...238 ...
Page 300: ...Chapter 13 Content Filtering Reports ZyWALL 2WG User s Guide 300 ...
Page 348: ...Chapter 14 IPSec VPN ZyWALL 2WG User s Guide 348 ...
Page 378: ...Chapter 15 Certificates ZyWALL 2WG User s Guide 378 ...
Page 384: ...384 ...
Page 426: ...Chapter 20 Bandwidth Management ZyWALL 2WG User s Guide 426 ...
Page 479: ...479 PART V Logs and Maintenance Logs Screens 481 Maintenance 511 ...
Page 480: ...480 ...
Page 485: ...Chapter 26 Logs Screens ZyWALL 2WG User s Guide 485 Figure 304 LOGS Log Settings ...
Page 510: ...Chapter 26 Logs Screens ZyWALL 2WG User s Guide 510 ...
Page 530: ...530 ...
Page 558: ...Chapter 30 WAN and Dial Backup Setup ZyWALL 2WG User s Guide 558 ...
Page 564: ...Chapter 31 LAN Setup ZyWALL 2WG User s Guide 564 ...
Page 570: ...Chapter 32 Internet Access ZyWALL 2WG User s Guide 570 ...
Page 574: ...Chapter 33 DMZ Setup ZyWALL 2WG User s Guide 574 ...
Page 578: ...Chapter 34 Route Setup ZyWALL 2WG User s Guide 578 ...
Page 582: ...Chapter 35 Wireless Setup ZyWALL 2WG User s Guide 582 ...
Page 594: ...Chapter 37 IP Static Route Setup ZyWALL 2WG User s Guide 594 ...
Page 614: ...Chapter 38 Network Address Translation NAT ZyWALL 2WG User s Guide 614 ...
Page 632: ...Chapter 40 Filter Configuration ZyWALL 2WG User s Guide 632 ...
Page 668: ...Chapter 44 System Maintenance Menus 8 to 10 ZyWALL 2WG User s Guide 668 ...
Page 672: ...Chapter 45 Remote Management ZyWALL 2WG User s Guide 672 ...
Page 680: ...Chapter 46 IP Policy Routing ZyWALL 2WG User s Guide 680 ...
Page 686: ...686 ...
Page 692: ...Chapter 48 Troubleshooting ZyWALL 2WG User s Guide 692 ...
Page 702: ...Chapter 49 Product Specifications ZyWALL 2WG User s Guide 702 ...
Page 704: ...704 ...
Page 712: ...Appendix A Pop up Windows JavaScripts and Java Permissions ZyWALL 2WG User s Guide 712 ...
Page 740: ...Appendix D Common Services ZyWALL 2WG User s Guide 740 ...
Page 768: ...Appendix G Legal Information ZyWALL 2WG User s Guide 768 ...
Page 774: ...Appendix H Customer Support ZyWALL 2WG User s Guide 774 ...