D-Link DES-3326 User Manual page 357

24-port NWay Ethernet Switch User's Guide
DNS Relay
DNS relay enables end stations to use a DNS server to resolve
domain names into IP addresses, even if the server and the end
station are not on the local IP interface.
If the DNS server and end station are on the same IP interface,
no relay is necessary. If the servers and the end stations are on
different IP interfaces, a relay agent is necessary for the switch
to forward the messages.
The relay agent forwards these packets between IP interfaces,
and therefore must know the IP addresses of the DNS servers
and their respective subnet names (or IP interface names).
When the switch receives packets destined for a DNS server, it
forwards them to specific servers as defined in the following
configuration. The switch also forwards packets from the DNS
servers to the appropriate subnets.
The first task is to set some parameters for the relay agent to
decide whether or not to forward a given DNS packet.
Figure 7-56. DNS Relay Setup Screen
Web-Based Network Management 341