WLAN AP ROUTER 802.11N17823 Dynamic DNSWhen you want your internal server to be accessed by usingDNS name rather than using the dynamic IP address, you canuse the DDNS service. The DDNS server allows to alias adynamic IP address to a static hostname.This chapter provides you an overview of the Dynamic DNSfeature of the modem and configuration details related to it.OverviewIf some host has a dynamic IP address that keeps changingfrequently, it is difficult to keep updating the IP record that isassociated with the domain name of this host in the zone files.This will result in non-accessibility of this host on the Internet.Dynamic DNS service allows to keep mapping of a dynamic IPaddress of such host to a static hostname. Dynamic DNSservices are provided by many websites. The host needs toregister with some website and get a domain name. When theIP address of the host changes, it just needs to send a messageto the website that's providing dynamic DNS service to this host.For this to work, an automated update client needs to beimplemented. These update clients send update messages tothe servers whenever there is some change in the IP address ofthat host. Then, the server updates the entries for that host andreplies back with some return code.Above Figure explains one such scenario in which a host gets adynamic IP address for itself from a DHCP server. As the hosthas registered with one of the dynamic DNS service providerson the Internet, it sends an update message to the serviceprovider with host name and changed IP address. The serviceprovider updates the new IP address of the host in the zonefiles that have entry for that host name and replies back withsome return code. The return code communicates the successor failure of the update message. This process is repeatedevery time the host's IP address changes.
