Re: How does RoundRobin flag work?
From: Peter Steele (psteele_at_z-force.com)
Date: 07/16/04
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Date: Fri, 16 Jul 2004 07:55:21 -0700
Okay, I've got it working, sort of. I created three A records for host
"test" that represent the IP addresses of three existing systems in the same
subnet (lets call them test1, test2, and test3). When I do a nslookup on
test it returns a rotated list on each request. However, if I do a ping
command, it always returns the same address unless I do a dnsflush between
each ping. I then tried opening a command prompt and entering the command
dir \\test\c$
and it came back with the error
You were not connected because a duplicate name exists on the network.
Go to System
in Control Panel to change the computer name and try again.
If I reference one of the systems directly, e.g. \\test1\c$, instead of
using test, it has no problems accessing the system. As one final test, I
went to Internet Explorer and entered the URL
It said if could not find the file though, whereas
works fine.
So, this feature isn't behaving the way I thought it would. Is this user
error or correct behavior. Can I only take advantage of the feature
programmatically?
"Roger Abell" <mvpNOSpam@asu.edu> wrote in message
news:ebmsgosaEHA.596@TK2MSFTNGP11.phx.gbl...
> A few points to keep in mind.
> Client caching can get in the way of seeing the effect of
> pseudo-roundrobin ordering. Use ipconfig /flushdns on
> the client to empty the caching resolver's cache so that it
> actually does really send the next query to the DNS server.
> When there are multiple A records for a name, and the use
> of pseudo-roundrobin ordering is enabled, then the list of
> IPs returned will start a successive IPs with each query.
> If other clients query the name in between two of your test
> trials this will cause the IP ordering to advance accordingly.
> If your test client is on the same subnet as one of the interfaces
> of the DNS server, and one of the IPs for the name queried is
> also on this subnet, and you have subnet ordering enabled in
> the DNS server settings, then this will control what you see
> returned as the IP list.
> --
> Roger Abell
> Microsoft MVP (Windows Server System: Security)
> MCSE (W2k3,W2k,Nt4) MCDBA
> "Peter Steele" <psteele@z-force.com> wrote in message
> news:%23jCVcpraEHA.3752@TK2MSFTNGP12.phx.gbl...
> > I read that the Windows DNS supports a flag called RoundRobin which lets
> you
> > perform a primitive round-robin load balancing. Can anyone explain how
to
> > set this up? When I read this I thought it would work like this:
> >
> > ping mysystem.domain.com
> > ...192.168.1.1
> >
> > ping mysystem.domain.com
> > ...192.168.1.2
> >
> > ping mysystem.domain.com
> > ...192.168.1.3
> >
> > and so on, returning a different address each time a DNS lookup has to
be
> > performed. I created multiple A records for a host and tried this though
> but
> > it always returned the first address in the list. If I do a nslookup on
> the
> > name, it returns all A addresses as a list.
> >
> > So how is this feature supposed to be used? Alternatively, if someone
can
> > suggest an alternative way to implement a simple round-robin load
> balancing
> > like this, I'd appreciate the advice.
> >
> >
> >
>
>
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