Intermittent total loss of DNS

Hi,

I have several PCs on a workgroup LAN, connected to the internet via
some routers.

All the PCs work fine, except one. It's a newly built one, win2000
with all the updates, all the best hardware I could get, and after it
hasn't been used for say an hour, DNS fails. Direct IP pings etc are
always just fine, and it always sees other machines on the office LAN.

I found some article on google suggesting that I turn off the DNS
service, and this definitely does help, but then one is relying on the
ISP's nameserver for every lookup instead of using the windows' DNS
cache, so it's slow. It still fails sometimes, though that could just
be loading on the ISP's nameserver.

I have tried sequences like

ipconfig /flushdns
ipconfig /renew
ipconfig /all

which appear to sometimes bring it back, but not always.

I have tried to put the ISP's nameserver IPs into both windows network
config and the router, but it makes no difference.

It used to work fine; the problem started after I did something, but I
can't see what. It isn't site specific; ALL name lookups just fail,
and then come back after a minute or a few. It however tends to be OK
if I just keep browsing. It's leaving it alone for many minutes that
tends to kill it.

Can anyone suggest where I could look?


Peter.
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Peter wrote on Mon, 21 Mar 2005 18:58:22 +0000:

> Hi,
>
> I have several PCs on a workgroup LAN, connected to the internet via
> some routers.
>
> All the PCs work fine, except one. It's a newly built one, win2000
> with all the updates, all the best hardware I could get, and after it
> hasn't been used for say an hour, DNS fails. Direct IP pings etc are
> always just fine, and it always sees other machines on the office LAN.
>
> I found some article on google suggesting that I turn off the DNS
> service, and this definitely does help, but then one is relying on the
> ISP's nameserver for every lookup instead of using the windows' DNS
> cache, so it's slow. It still fails sometimes, though that could just
> be loading on the ISP's nameserver.
>
> I have tried sequences like
>
> ipconfig /flushdns
> ipconfig /renew
> ipconfig /all
>
> which appear to sometimes bring it back, but not always.
>
> I have tried to put the ISP's nameserver IPs into both windows network
> config and the router, but it makes no difference.
>
> It used to work fine; the problem started after I did something, but I
> can't see what. It isn't site specific; ALL name lookups just fail,
> and then come back after a minute or a few. It however tends to be OK
> if I just keep browsing. It's leaving it alone for many minutes that
> tends to kill it.
>
> Can anyone suggest where I could look?

It sounds like DNS responses are timing out. IIRC the first time you get a
timeout the DNS Client fails over to the 2nd DNS IP you have listed. Then if
that has a timeout at some point it will fail over to the next one. If it's
at the end of the list of DNS server it *should* fail back to the first,
however I'm pretty sure there's a bug (in 2K at least there was, not sure if
it was fixeD) that would actually fail to switch back to the first DNS
server IP - you'd be stuck with no DNS servers to look up. I disabled the
DNS Client on all my 2K PCs and never looked back, but then again I run my
own full DNS servers here at work for all my PCs to use and so are as good
as having a local cache.

Have you checked in the event logs to see if there's anything recorded that
might give a clue as to what's going on? Do you have a router/firewall that
might be throttling or blocking DNS responses and so this machine thinks
that the DNS server is down, and therefore is failing over to the next one?

Dan

"Spack" <(E-Mail Removed)> wrote

>It sounds like DNS responses are timing out. IIRC the first time you get a
>timeout the DNS Client fails over to the 2nd DNS IP you have listed. Then if
>that has a timeout at some point it will fail over to the next one. If it's
>at the end of the list of DNS server it *should* fail back to the first,
>however I'm pretty sure there's a bug (in 2K at least there was, not sure if
>it was fixeD) that would actually fail to switch back to the first DNS
>server IP - you'd be stuck with no DNS servers to look up. I disabled the
>DNS Client on all my 2K PCs and never looked back, but then again I run my
>own full DNS servers here at work for all my PCs to use and so are as good
>as having a local cache.
>
>Have you checked in the event logs to see if there's anything recorded that
>might give a clue as to what's going on? Do you have a router/firewall that
>might be throttling or blocking DNS responses and so this machine thinks
>that the DNS server is down, and therefore is failing over to the next one?

Thank you for this. The problem is that other PCs on the same LAN work
just fine, before, during and after I have this DNS problem. So I
can't see how it can be anything outside this PC. I will check the
event log tomorrow.

My router has a DHCP server as they usually do but it doesn't have a
DNS cache.


Peter.
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On Mon, 21 Mar 2005 18:58:22 +0000, (E-Mail Removed) (Peter) wrote:

Re: DNS problem with Windows 2000

http://ntcanuck.com/ TreeWalk DNS

I've had no DNS problems in over 2 years since I started using this.
It costs nothing, install and forget.

--
ddm

"Spack" <(E-Mail Removed)> wrote:

>Have you checked in the event logs to see if there's anything recorded that
>might give a clue as to what's going on?

There's nothing in the event log that corresponds to this problem, or
to anything else in the time frame.


Peter.
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Dave Mason <(E-Mail Removed)> wrote

>Re: DNS problem with Windows 2000
>
>http://ntcanuck.com/ TreeWalk DNS
>
>I've had no DNS problems in over 2 years since I started using this.
>It costs nothing, install and forget.

Tried it, it works, and if I don't say anything in the next few days
then it's fixed it THANK YOU.


Peter.
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