SMC Networks SMC7204BRA manual Configuring DNS Relay, Configuring DNS Server Addresses

Configuring DNS Server Addresses

•Dynamically from a DHCP pool:

You can configure the DHCP Server feature on the ADSL Barricade and create an address pool that specifies the DNS addresses to be distributed to the PCs. Refer to Configuring DHCP Server for instructions on creating DHCP address pools.

In either case, you can specify the actual addresses of the ISP's DNS servers (on the PC orin the DHCP pool), or you can specify the address of the LAN port on the ADSL Barricade (e.g. 192.168.1.1). When you specify the LAN port IP addresses, the device performs DNS relay, as described in the following section.

Note: If you specify the actual DNS addresses on the PCs or in the DHCP pool, the DNS relay feature is not used.

Configuring DNS Relay

When you specify the ADSL Barricade's LAN port IP addresses as the DNS addresses, 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 ADSL Barricade must maintain 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 Configuring PPP Interfaces on page 105 for instructions

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