Win2k caches ip addr. after name resolution from dns?

Marc.Thach at radianz.com Marc.Thach at radianz.com
Tue Sep 25 08:58:21 UTC 2001



This may be the link to which Pete refers:
http://support.microsoft.com/directory/article.asp?ID=KB;EN-US;Q263558
Marc TXK



                                                                                                                   
                    Pete Ehlke                                                                                     
                    <lists-djbdns at r        To:     bind-users at isc.org                                              
                    fc822.net>             cc:                                                                     
                    Sent by:               Subject:     Re: Win2k caches ip addr. after name resolution from dns?  
                    bind-users-boun                                                                                
                    ce at isc.org                                                                                     
                                                                                                                   
                                                                                                                   
                    25/09/2001                                                                                     
                    07:08                                                                                          
                                                                                                                   
                                                                                                                   





* Danny Mayer <mayer at gis.net> said, on [010924 20:03]:
>
> At 09:23 PM 9/24/01, Sanjivendra Nath wrote:
>
> >Is there anyway for us to force the MS clients (namely, IE 5.0) to go to
the
> >DNS for name resolution always, or at least limit the time during which
it
> >caches the ip address of a site?
>
> No.  That's totally under the control of the designer of the client. Why
would
> you think otherwise?  Caching can be limited to the extent that the
client
> wants to by giving the address a TTL that you desire.
>
Well, yes and no. IE 5 seems to do a fairly decent job with dns response
caching, but win2k itself, at the OS level, is almost irretrievably
broken in this respect. It implements a local resolver cache, similar to
Sun's nscd, that cannot be turned off and which seems to, at the very
least, have its own ideas about TTL regardless of the value contained in
the RR itself. It also seems to do odd things with TTLs when an A and a
CNAME record that points to it have different TTLs, and it dosne't
behave as one expects with round robin records. When confronted with a
round-robin response, the w2k resolver cache seems to simply pick one
record and ignore the rest. This is the behaviour that the OP is seeing.

There used to be a TechNet article that described how to reduce the
resolver cache's TTL value to one second, effectively kneecapping it. I've
lost the URL, though, and a half hour of searching microsoft.com has
failed to turn it up :/

-Pete







More information about the bind-users mailing list