Win2k caches ip addr. after name resolution from dns?

[Sanjivendra Nath]

Danny, thanks for the response.  My real motivation for asking this is the
following:

I'd like to do load testing using simulated clients spread across 4 client
boxes hitting the 2 web-servers.  Unfortunately, the w2k box is locking all
the 300+ virtual clients running on that physical box into talking with just
one of the webservers.  Maybe TTL is the way to go for now, or use an
earlier version of IE which runs on win98.  Where would I setup the TTL
though?

I haven't tried Netscape though - I will try that and see what happens.

- Sanju.


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.

Did you try Netscape Communicator?

>I've tried 4 clients now against my DNS running Bind9 on linux with
>roundrobin setup to 2 webservers behind it.
>
>* linux client, win95, win98 - consecutive pings average out to 50% load on
>each webserver.
>
>* win2k - consecutive pings sticks to the first ip address of the webserver
>served by my DNS.

This seems like the right behavior to me.  You don't want to have the client
constantly requesting an IP Address every time it wants another page from
your web server. The 1.1 HTTP protocol has a Keep-Alive header option to
allow it to keep the connection open while it's retrieving multiple files
from the
server.  It it didn't do that downloads would be much, much longer.

If you are worried about your Web Server going down and people being unable
to access it, you should be worrying about replacing your Web server with
something more reliable. Placing the burden on DNS to deal with a Web server
reliability problem is a way of avoiding solving the real problem.

         Danny