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VisionNet 202ER-4 ADSL Ethernet Router User’s Guide
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Configuring DNS Relay
When you specify the device's LAN port IP address as the DNS
address, then the ADSL/Ethernet automatically performs “DNS
relay”; i.e., because the device itself is not a DNS server, it forwards
domain name lookup requests that it receives on its LAN port to a
DNS server at the ISP. It then relays the response to the PC.
address, then the ADSL/Ethernet automatically performs “DNS
relay”; i.e., because the device itself is not a DNS server, it forwards
domain name lookup requests that it receives on its LAN port to a
DNS server at the ISP. It then relays the response to the PC.
When performing DNS relay, the VisionNet 202ER-4 must maintain
the IP addresses of the DNS servers it contacts. It can learn these
addresses in either or both of the following ways:
the IP addresses of the DNS servers it contacts. It can learn these
addresses in either or both of the following ways:
Learned 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 13 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.
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 13 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.
Configured 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.
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.
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, configure it to "Use
DNS" so that the DNS server addresses it learns are used
for DNS relay.
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
as follows: