TRENDnet TDM-C400, Руководство пользователя

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TDM-E400 / TDM-C400 ADSL2+ Ethernet Modem Router User’s Manual
104
Configuring DNS Relay
When you specify the Ethernet Modem Router 's LAN interface 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 Ethernet Modem 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:
f
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 “Configuring PPP
Interfaces,” on page 61 for related instructions. 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 is advantageous in that you will not need
to reconfigure the PCs or the ADSL2+ Ethernet Modem
Router if the ISP changes their DNS addresses.
f
Configured on the ADSL/Ethernet Modem 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 can 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 Modem
Router's LAN IP address as their DNS server address using
either of the following methods:
f
by assigning the LAN IP address statically to each PC
f
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 ADSL2+ Ethernet
Modem Router as follows: