Session DNS

[Kevin Darcy]

Chris wrote:

>Instead of using hosts and lmhosts in Windows 2000, we want to add a
>temporary IP/Hostname entry to a client workstation by using script.
>e.g. 192.3.4.5     web01.mycompany.com
>
>Users can add the entry by running the script manually when their
>application required this mapping. When system shutdown, the entry
>will be cleared automatically.
>
>Is it possible to do that?
>
Well, it's certainly *possible*, since there is a protocol extension to 
DNS called Dynamic Update, which allows authorized clients to update a 
live DNS database. But I'm aware of no software -- user-friendly 
software at least -- that gives this client functionality to PCs. 
Perhaps you should ask about that in a PC utilities-type 
newsgroup/mailing-list.

Also, from an infrastructure perspective, how do you propose to deal 
with the inevitable naming conflicts, e.g. two different users want to 
name their PC web01.mycompany.com? Or users who delete each other's 
names? Or forget to delete names when they're done with it, thus 
creating a scrapheap of obsolete names in your DNS database?

Be aware that with BIND, once you turn on Dynamic Update for a zone, 
basically you're committing yourself to using Dynamic Update for *all* 
updates to the zone, since it's no longer safe to make manual changes to 
the zone file. For that matter, it's really not even safe to *look* at 
the zone file, since you can never be sure whether it's up-to-date with 
all of the latest Dynamic Updates. The lack of direct editability and/or 
viewability could cause major disruption to your DNS maintenance 
processes. Of course, you might be able to avoid this nastiness if you 
can convince your users to put all of the dynamic stuff into a separate 
delegated subzone, e.g. dynamic.mycompany.com or pc.mycompany.com. Then 
you'd only enable Dynamic Update for the subzone, and you could continue 
to maintain the main zone the way you always have.

                                                                         
                                       - Kevin