Dynamic DNS - Background

Background

The Internet uses an IP address to refer to all resources on the Internet in a fashion similar to phone numbers. Like phone numbers, most IP addresses cannot be easily remembered, and are looked up in the internet equivalent of a phone book. This is the Domain Name System, or DNS. DNS automatically translates human-readable hostnames like "wikipedia.org" into the corresponding IP address, 208.80.152.201.

DNS is based on a distributed database that takes some time to update globally. When DNS was first introduced, the database was small and could be easily maintained by hand. As the system grew this task became difficult for any one site to handle, and a new management structure was introduced to spread out the updates among many domain name registrars. Registrars today offer end-user updating to their account information, typically using a web-based form, and the registrar then pushes out update information to other DNS servers.

Due to the distributed nature of the DNS systems and its registrars, updates to the global DNS system may take hours to distribute. Thus DNS is only suitable for services that do not change their IP address very often, as is the case for most large services like Wikipedia or Google. Smaller services, however, are generally much more likely to move from host to host over shorter periods of time. Servers being run on certain types of internet service provider, cable modems in particular, are likely to change their IP address over very short periods of time, on the order of days or hours.