The second kind of dynamic DNS permits lightweight and immediate updates often using an update client, which do not use the RFC2136 standard for updating DNS records.
These clients provide a persistent addressing method for devices that change their location, configuration or IP address frequently.
DHCP became an important tool for ISPs as well to manage their address spaces for connecting home and small-business end-users with a single IP address each by implementing network address translation (NAT) at the customer-premises router.
The private network behind these routers uses address space set aside for these purposes (RFC 1918), masqueraded by the NAT device.
The first is "dynamic DNS updating" which refers to systems that are used to update traditional DNS records without manual editing.
These mechanisms are explained in RFC 2136, and use the TSIG mechanism to provide security.
Dynamic DNS is a system that addresses the problem of rapid updates.
The term is used in two contexts which, while technically similar, have very different purposes and user populations.
In the initial stages of the Internet (ARPANET) addressing of hosts on the network was achieved by static translation tables that mapped hostnames to IP addresses.
The tables were maintained manually in form of the host file.
Due to the distributed nature of the DNS systems and its registrars, updates to the global DNS system may take hours to distribute.