<<We were talking about IP Filter which is used to identify clients, and not about the ability to identify servers by their DNS names!>>
Yes, yes I know, I think we are just mis-understanding one another. You said:
<<These hostnames can be assigned to anyone. They are not permanent and may be assigned to another computer next week. DynDNS is dynamic DNS - just like dynamic IP. So it seems Radmin's IP Filter is not for you.
The server owner would need to be responsible about updating the access list. If in fact, the client's DNS was lost, and received by another person, the owner would need to remove that DNS from the trusted list. However, if that DNS was picked up by somebody else, that person would still need to know what the RAdmin server password is. So there really isn't a security risk at all.
So why use the ip filter at all? Well, in most cases the client will make sure that his/her ip address is udpated with that dyndns name. Why have a dynamic DNS at all if you're not going to keep it updated?
Also, the new version shouldn't have support for only dynamic DNS's! I, for example, have a DNS which is registered for another 3 years. This is a very good idea that should definitly be in future releases. However, Famatech might want to put a warning about dynamic DNS's in the help file of that new version.