Dynamically generating subdomains using subdomain-fu


I am using subdomain-fu for creating subdomains . My doubt is how
can we give the subdomains in the etc/hosts ,when the sub-domains are
dynamicallybeing created.

Ex: i created a subdomain called “user1” and i specified this in etc/
hosts file.So eveery time i cant specify the subdomain which is being
created.So can i ovecome this problem.