Once you understand what DNS
is and how IP addresses are assigned
it is easy to understand the role of Dynamic DNS.
The Dynamic DNS
is a system that maintains the association between a name
(eg: myhost.dnup.eu) and a machine
(server or router) by updating the IP address on time, which changes in time
Let's see a simple user story:
The NAS server (A)
of the local network accesses internet (D)
through the service provider (C)
The router (B)
has two addresses: a private (B1)
, chosen by the LAN administrator, and a public (B2)
The subject (E)
, owner of the LAN, wants to contact the server to retrieve a document, but to do so he must know the address (B2) which, being dynamic, changes with a certain frequency.
Fortunately (E) has a subscription to dnsUp
which, thanks to the update client
knows the public address B2 and keeps updated the association between the hostname myhost.dnup.eu and the router (B).
In this way (E), to access the NAS server (A) and all its services
, it must simply remember
the name "myhost.dnup.eu" that has been configured on dnsUp.