Some DDNS servers support the wildcard feature which allows the hostname, *.yourhost.dyndns.org, to be aliased to the same IP address as yourhost.dyndns.org. This feature is useful when there are multiple servers inside and you want users to be able to use things such as www.yourhost.dyndns.org and still reach your hostname.
"Some DDNS servers support the wildcard alias feature which can points *.yourhost.dyndns.org to your computers automatically. All aliases for your domain such as www.yourhost.dyndns.org, ftp.yourhost.dyndns.org and pop3.yourhost.dyndns.org etc will point to your computer by default due to Wildcard Alias. This allows users to access your computer using all types of derivatives of your domain name. This feature is useful when there are multiple servers in your LAN and you want users to be able to use different domain name and still reach your servers.