3Com S7906E - Switch, Configuration Manual

Page: 441 / 2621

1-3
DNS Proxy
Introduction to DNS proxy
A DNS proxy forwards DNS requests and replies between DNS clients and a DNS server.
As shown in Figure 1-2 , a DNS client sends a DNS request to the DNS proxy, which forwards the
request to the designated DNS server, and conveys the reply from the DNS server to the client.
The DNS proxy simplifies network management. When the DNS server address is changed, you only
need to change the configuration on the DNS proxy instead of on each DNS client.
Figure 1-2 DNS proxy networking application
Operation of a DNS proxy
1) A DNS client considers the DNS proxy as the DNS server, and sends a DNS request to the DNS
proxy, that is, the destination address of the request is the IP address of the DNS proxy.
2) The DNS proxy searches the local static domain name resolution table after receiving the request.
If the requested information exists in the table, the DNS proxy returns a DNS reply to the client.
3) If the requested information does not exist in the static domain name resolution table, the DNS
proxy sends the request to the designated DNS server for domain name resolution.
4) After receiving a reply from the DNS server, the DNS proxy forwards the reply to the DNS client.
Configuring the IPv4 DNS Client
Configuring Static Domain Name Resolution
Configuring static domain name resolution refers to specifying the mappings between host names and
IPv4 addresses. Static domain name resolution allows applications such as Telnet to contact hosts by
using host names instead of IPv4 addresses.
Follow these steps to configure static domain name resolution:
To do… Use the command… Remarks
Enter system view system-view ––
Configure a mapping between a host
name and an IPv4 address
ip host hostname ip-address
Required
Not configured by default.