Internet Security Router User
’s Manual
Chapter 8. Configuring DDNS
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8
Configuring DDNS
Dynamic DNS is a service that allows computers to use the same domain name, even when the IP address
changes from time to time (during reboot or when the ISP's DHCP server resets IP leases). Internet Security
Router connects to a Dynamic DNS service whenever the WAN IP address changes. It supports setting up the
web services such as Web server, FTP server using a domain name instead of the IP address. Dynamic DNS
supports the DDNS clients with the following features:
„ Update DNS records (addition) when an external interface comes up
„ Force DNS update
Dynamic DNS supports two modes, namely RFC-2136 DDNS Client and HTTP DDNS Client.
RFC-2136 DDNS Client
domain.com
ISR
Windows 2000
DNS Server
sl1000.domain.com
Figure 8.1. Network Diagram for RFC-2136 DDNS
Any interface status change to an external interface sends a DDNS update to the DNS server. When
connection to Primary DNS server fails, the Internet Security Router updates the Secondary DNS server.
When a DNS update is forced by the administrator, update is sent to the server for all active external interfaces.
HTTP Dynamic DNS Client
HTTP DDNS client uses the mechanism provided by the popular DDNS service providers for updating the
DNS records dynamically. In this case, the service provider updates DNS records in the DNS. Internet Security
Router uses HTTP to trigger this update.
The Internet Security Router supports HTTP DDNS update with the following service providers: