Duck DNS is an free dynamic DNS. Duck DNS is a free service which will point a DNS to an IP of your choice. DDNS is a handy way for you to refer to a server/router with an easily rememberable name, where the servers ip address is likely to change. When your router reconnects, or ec2 server reboots, its ip address is set by the provider of that connection, this means it may update at any time. Duck DNS offers accounts with up to 4 subdomains of duckdns.org.