R0106-HP MSR Router Series Layer 3 - IP Services Configuration Guide(V7)

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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 by only IPv4 DNS, and it is used to update the mappings between domain names
and IPv4 addresses.
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.
Figure 46 DDNS application
With the DDNS client configured, a device can dynamically update the latest mapping between its
domain name and IP address on the DNS server through DDNS servers.
HTTP server
DDNS client
DDNS server
DNS server
IP network
HTTP client