H3C Technologies H3C S5560 Series Switches - Manual (Page 121)

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Configuring DDNS
Overview
DNS provides only the static mappings between domain names and IP addresses. When the IP address
of a node changes, your access to the node fails.
Dynamic Domain Name System (DDNS) can dynamically update the mappings between domain names
and IP addresses for DNS servers.
DDNS is supported only by IPv4 DNS, and it is used to update the mappings between domain names
and IPv4 addresses.
NOTE:
The term "interface" in this chapter collectively refers to Layer 3 interfaces, including VLAN interfaces and
Layer 3 Ethernet interfaces. You can set an Ethernet port as a Layer 3 interface by using the port link-mode
route command (see Layer 2—LAN Switching Configuration Guide).
DDNS application
As shown in Figure 46 , DDNS works on the client-server model.
• DDNS client—A device that needs to update the mapping between its domain name and its IP
address dynamically on the DNS server when its IP address changes. An Internet user typically
accesses an application layer server such as an HTTP server or an FTP server by using the server's
domain name. When its IP address changes, the application layer server runs as a DDNS client. It
sends a request to the DDNS server for updating the mapping between its domain name and its IP
address.
• DDNS server—Informs the DNS server of latest mappings. When receiving the mapping update
request from a DDNS client, the DDNS server tells the DNS server to re-map the domain name and
the 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.