Well DA-150N, Руководство пользователя

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User’s Guide Configuring your Computers
34
Dynamic DNS Configuration
Overview of Dynamic DNS
If some host has a dynamic IP address that keeps changing
frequently, it is difficult to keep updating the IP record that is
associated 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 IP
address of such host to a static hostname. Dynamic DNS
services are provided by many websites. The host needs to
register with some website and get a domain name. When the
IP address of the host changes, it just needs to send a message
to the website that's providing dynamic DNS service to this host.
For this to work, an automated update client needs to be
implemented. These update clients send update messages to
the servers whenever there is some change in the IP address of
that host. Then, the server updates the entries for that host and
replies back with some return code.
Above Figure explains one such scenario in which a host gets a
dynamic IP address for itself from a DHCP server. As the host
has registered with one of the dynamic DNS service providers
on the Internet, it sends an update message to the service
provider with host name and changed IP address. The service
provider updates the new IP address of the host in the zone
files that have entry for that host name and replies back with
some return code. The return code communicates the success
or failure of the update message. This process is repeated
every time the host's IP address changes.
If the dynamic DNS service provider is notified of the same IP
address again and again, then it considers it an abuse and
might block the host name. To avoid this scenario, the IP
address that was successfully updated to the ISP is stored on
the unit. Whenever we receive an IP address change
notification, the new IP address is compared with the IP address
that was stored on the last update. If they differ, then only an
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