ATL Telecom AM30 - Manual (Page 80)

80 ATL Telecom User Guide
AM30
Configuring DNS Relay
When you specify the ROUTER's LAN port IP address as the DNS address, then the device
automatically performs “DNS relay”; i.e., because the device itself is not a DNS server, it forwards
domain name lookup requests it receives from the LAN PCs to a DNS server at the ISP. It then
relays the DNS server’s response to the PC.
When performing DNS relay, the ROUTER must maintain the IP addresses of the DNS servers it
contacts. It can learn these addresses in either or both of the following ways:
fLearned through PPP: If the device uses a PPP
connection to the ISP, the primary and secondary
DNS addresses can be learned via the PPP protocol.
To use this method, the "Use DNS" checkbox must
be selected in the PPP interface properties. (See
Chapter 0 for instructions on configuring your PPP
interface. Note that you cannot change this property
by modifying an existing PPP interface; you must
delete the interface and recreate it with the new
setting.)
Using this option provides the advantage that you
will not need to reconfigure the PCs or the
ADSL/Ethernet router if the ISP changes their DNS
addresses.
fConfigured on the ADSL/Ethernet router: You
can use the device's DNS feature to specify the ISP's
DNS addresses. If the device also uses a PPP interface
with the "Use DNS" property enabled, then these
configured addresses will be used in addition to the
two addresses learned through PPP. If "Use DNS" is
not enabled, or if a protocol other than PPP is used
(such as EoA), then these configured addresses will
be used as the primary and secondary DNS
addresses.
Follow these steps to configure DNS relay:
1. Configure the LAN PCs to use the ADSL/Ethernet router's
LAN IP address as their DNS server address—by assigning
the LAN IP address statically to each PC, or by inputting the
LAN IP address or the address 0.0.0.0 as the DNS address
in the DHCP server pool used by the PCs.
2. If using a PPP connection to the ISP, click the "Use DNS"
check box so that the DNS server addresses it learns are
used for DNS relay.
Or, ...
If not using a PPP connection (or if you want to specify DNS
addresses in addition to those learned through PPP),
configure the DNS addresses on the ADSL/Ethernet router