Asus RX3042H - Manual (Page 63)

RX3042H User's Manual DHCP Server Configuration
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Note: If you specify the actual DNS addresses on the
PCs or in the DHCP pool, the DNS relay feature is not
used.
6.2.3 Configuring DNS Relay
When you specify the deviceʼs LAN port IP address as the DNS
address, then the Internet Security Router automatically performs
“DNS relay”; i.e., because the device itself is not a DNS server, it
forwards domain name lookup requests from the LAN PCs to a
DNS server at the ISP. It then relays the DNS serverʼs response to
the PC.
When performing DNS relay, the RX3042H 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 PPPoE or Dynamic IP Connection: If the
RX3042H uses a PPPoE (see section 5.2.2 PPPoE or 5.2.3
PPPoE Unnumbered) or Dynamic IP (see section 5.2.4
Dynamic IP) connection to the ISP, the primary and secondary
DNS addresses can be learned via the PPPoE protocol. Using
this option provides the advantage that you will not need to
reconfigure the PCs or the RX3042H if the ISP changes their
DNS addresses.
• Configured on the RX3042H: You can also specify the ISPʼs
DNS addresses in the WAN configuration page as shown in
Figure 5.3, Figure 5.4 or Figure 5.5 or Figure 5.6.
Follow these steps to configure DNS relay:
1. Enter LAN IP in the DNS Server IP Address field in DHCP
configuration page as shown in Figure 6.1.
2. Configure the LAN PCs to use the IP addresses assigned by
the DHCP server on the Internet Security Router, or enter the
Internet Security Routerʼs LAN IP address as their DNS server
address manually for each PC on your LAN.
Note: DNS addresses that are assigned to LAN PCs
prior to enabling DNS relay will remain in effect until
the PC is rebooted. DNS relay will only take effect
when a PCʼs DNS address is the LAN IP address.
Similarly, if after enabling DNS relay, you specify a