R3166-R3206-HP High-End Firewalls Network Management Configuration Guide-6PW101

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DDNS configuration
DDNS overview
Introduction
Although DNS allows you to access nodes in networks using their domain names, it provides only the
static mappings between domain names and IP addresses. When you use the domain name to access
a node whose IP address has changed, your access will fail because DNS leads you to the IP address
that is no longer where the node resides.
Dynamic Domain Name System (DDNS) can dynamically update the mappings between domain names
and IP addresses for DNS servers to direct you to the latest IP address corresponding to a domain name.
DDNS networking application
Figure 93 DDNS networking application
As shown in Figure 93, DDNS works on the client-server model comprising the DDNS client and the
DDNS server.
• DDNS client: Refers to servers such as HTTP and FTP servers. The Internet users usually access these
servers using domain names. When its IP address changes, the DDNS client will inform the DDNS
server of its new mapping.
• 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 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.