H3C Technologies H3C WX3000E Series Wireless Switches - Manual (Page 261)

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Configuring DDNS
Support for DDNS depends on the device model. For more information, see " About the H3C Access
Controllers Web-Based Configuration Guide ."
Overview
DNS allows you to access nodes in networks using their domain names. However, it provides only the
static mappings between domain names and IP addresses. When you use a domain name to access a
node whose IP address has changed, your access fails because DNS leads you to the IP address where
the node no longer resides.
Dynamic Domain Name System (DDNS) dynamically updates the mappings between domain names
and IP addresses for DNS servers. Through DDNS, you can always access the latest IP address
corresponding to a domain name.
As shown in
Figure 214 , DDNS works on the client-server model.
• DDNS client—A device that needs the DNS server to update the mapping between the domain
name and IP address of the device dynamically. An Internet user typically uses a domain name to
access a server that provides application layer services, such as an HTTP server or an FTP server.
When the IP address of such a server changes, the server runs as a DDNS client and sends a
request to the DDNS server for updating the mapping between the domain name and the IP
address.
• DDNS server—Informs the DNS server of latest mappings. After it receives the mapping update
request from a DDNS client, the DDNS server tells the DNS server to re-map between the domain
name and IP address of the DDNS client. Therefore, the Internet users can use the same domain
name to access the DDNS client even if the IP address of the DDNS client has changed.
Figure 214 DDNS networking application
The DDNS update process does not have a unified standard and depends on the DDNS server that the
DDNS client contacts. The well-known DDNS service providers include www.3322.org, www.oray.cn
(also known as the PeanutHull server), and www.dyndns.com .