Each ISP may provide a set of DNS servers for DNS lookups. This setting
specifies the DNS (Domain Name System) servers to be used when a DNS lookup
is routed through this connection.
Selecting Obtain DNS server address automatically results in the DNS servers
assigned by the PPPoE server to be used for outbound DNS lookups over the
WAN connection.
(The DNS servers are obtained along with the WAN IP address assigned from the
PPPoE server.)
When Use the following DNS server address(es) is selected, you can enter
custom DNS server addresses for this WAN connection into the DNS server 1
and DNS server 2 fields.