DDNS (Dynamic DNS) is a service that maps Internet domain names to IP addresses. DDNS serves a similar purpose to the Internet’s Domain Name System (DNS): DDNS allows anyone hosting a Web or FTP server to advertise a public name to prospective users.

Unlike DNS that only works with static IP addresses, DDNS is designed to also support dynamic IP addresses, such as those assigned by a DHCP server. That makes DDNS a good fit for home networks, which normally receive dynamic public IP addresses from their Internet provider that occasionally change.