Nortel BSR252 Configuration - Basics page 84

84 Chapter 5 System screens
Table 8 System general setup
Label
System DNS
Servers (if
applicable)
First DNS Server
Second DNS
Server
Third DNS Server
NN47923-500
Description
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 Business Secure
Router uses a system DNS server (in the order you specify here) to
resolve domain names for VPN, DDNS and the time server.
Select From ISP if your ISP dynamically assigns DNS server
information (and the Business Secure Router WAN IP address). The
field to the right displays the (read-only) DNS server IP address that
the ISP assigns. If you chose From ISP, but the Business Secure
Router has a fixed WAN IP address, From ISP changes to None
after you click Apply. If you chose From ISP for the second or third
DNS server, but the ISP does not provide a second or third IP
address, From ISP changes to None after you click Apply.
Select User-Defined if you have the IP address of a DNS server. The
IP address can be public or a private address on your local LAN.
Enter the DNS server's IP address in the field to the right.
A User-Defined entry with the IP address set to 0.0.0.0 changes to
None after you click Apply. A duplicate User-Defined entry changes
to None after you click Apply.
Select None if you do not want to configure DNS servers. If you do
not configure a system DNS server, you must use IP addresses when
configuring VPN, DDNS and the time server.
Select Private DNS 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 in the LAN IP screen to use DNS Relay.
You must also configure a VPN branch office rule since the Business
Secure Router uses a VPN tunnel when it relays DNS queries to the
private DNS server. The rule must also have an IP policy that
includes the LAN IP address of the Business Secure Router as a
local IP address and the IP address of the DNS server as a remote IP
address.
A Private DNS entry with the IP address set to 0.0.0.0 changes to
None after you click Apply. A duplicate Private DNS entry changes
to None after you click Apply.