P-2812HNU-51c User’s Guide
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CHAPTER 17
DNS Route
17.1 Overview
DNS (Domain Name System) is for mapping a domain name to its corresponding
IP address and vice versa. The DNS server is extremely important because
without it, you must know the IP address of a machine before you can access it.
In addition to the system DNS server(s), each WAN interface (service) is set to
have its own static or dynamic DNS server list. You can configure a DNS static
route to forward DNS queries for certain domain names through a specific WAN
interface to its DNS server(s). The P-2812HNU-51c uses a system DNS server (in
the order you specify in the WAN > Internet Connection screen) to resolve
domain names that do not match any DNS routing entry. After the P-2812HNU-
51c receives a DNS reply from a DNS server, it creates a new entry for the
resolved IP address in the routing table.
In the following example, the DNS server 168.92.5.1 obtained from the WAN
interface ptm0.100 is set to be the system DNS server. The DNS server
10.10.23.7 is obtained from the WAN interface ppp1.123. You configure a DNS
route for *example.com to have the P-2812HNU-51c forward DNS requests for the
domain name mail.example.com through the WAN interface ppp1.123 to the DNS
server 10.10.23.7.
Figure 154 Example of DNS Routing Topology
WAN
LAN
ptm0.100
ppp1.123
DNS:10.10.23.7
DNS:168.92.5.1
sip.service.com
mail.example.com
(Default)
