Can't find other domain controller

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fred flintstone

The company I work for has a large Win2000/Win2003 Active Directory
installation (some 20,000+ computers). I help run the Australian operations.

We have a single Win2000 Domain Controller at our office in Sydney, with
a 256kbps link to other offices overseas where there are numerous other
DCs, Exchange servers, DNS, WINS, GCs, etc.

The DC in Sydney is also a GC, DNS and WINS server.
There are other local DNS and WINS servers.

Unfortunalately our local DC is flakey and becomes very unresponsive
after about a week's uptime (seems to be running out of non-paged
memory) and we're working on getting a new DC to replace it.

In the meantime, when the local DC goes down (or equivalently becomes
unresponsive which forces us to do a hard reset) our client workstations
become unusable - we can't connect to local network drives and we can't
use Outlook (which connects to a local Exchange 2000 Server).

I have the DNS clients pointing to another DNS server other than the DC
and name resolution for internal and external works fine when the local
DC is down. I can ping other DCs overseas via their DNS names just fine
- no problem here.

I don't understand why our client workstations are unable to locate
another DC on the network when the local DC is down - I thought the DNS
was responsible for directing clients to a DC that is available/online.

How do I fix this problem?
 
fred flintstone said:
The company I work for has a large Win2000/Win2003 Active Directory
installation (some 20,000+ computers). I help run the Australian operations.

We have a single Win2000 Domain Controller at our office in Sydney, with
a 256kbps link to other offices overseas where there are numerous other
DCs, Exchange servers, DNS, WINS, GCs, etc.
Click to expand...
The DC in Sydney is also a GC, DNS and WINS server.
There are other local DNS and WINS servers.

Unfortunalately our local DC is flakey and becomes very unresponsive
after about a week's uptime (seems to be running out of non-paged
memory) and we're working on getting a new DC to replace it.
Click to expand...

Probably better to figure out what is causing it.

That is likely a software program which has
a memory leak -- and since it is non-paged pool
the chances are it is a service or driver.
In the meantime, when the local DC goes down (or equivalently becomes
unresponsive which forces us to do a hard reset) our client workstations
become unusable - we can't connect to local network drives and we can't
use Outlook (which connects to a local Exchange 2000 Server).
Click to expand...

"Can't connect" is pretty vague.
I have the DNS clients pointing to another DNS server other than the DC
and name resolution for internal and external works fine when the local
DC is down. I can ping other DCs overseas via their DNS names just fine
- no problem here.
Click to expand...

Well, did you test it explicitly to make sure that name
resolution is no problem when you have the "can't connect"?

Shares could well be a WINS problem -- since the
Master Browser won't find the Domain Master Browser
in a multiple subnet network without it -- IF "can't connect"
means "can't see the shares in Explorer or Network Neighborhood"
I don't understand why our client workstations are unable to locate
another DC on the network when the local DC is down - I thought the DNS
was responsible for directing clients to a DC that is available/online.
Click to expand...

If DNS is properly replicated.

What sort of DNS do you use for the Domain Zone?

Secondary? Or AD-Integrated?
How do I fix this problem?
Click to expand...

First we need to isolated it -- then fixing is usually easy.

Start with the basics, during the problem:

Can you ping? Name? Or just number?
If you can't ping or you know of a good reason for
not being able to do so (e.g., firewalls) then we
need to use Telnet or netcat to check IP connectivity.

Can you do see other computers in Net Neighborhood
during the problem?

Does: Net View \\ServerName
...work during the problem.

How about the IP of a server: Net View \\192.168.10.5

How about NSLookup of a server address?

What does NBTstat -r (and pay attention to the number
of names resolved by SERVER -- if the WINS server is
not right this may give a clue.)

Make sure all of the DNS and WINS clients -- and remember
that 'server machines' are name resolution clients -- have
ONLY the multiple internal (to your private network) DNS
servers listed and multiple WINS servers listed

If the clients have a mix of external or don't have an
alternate listed they will not work when the DC is sick
(since it is their DNS and WINS.)

Doublecheck DNS and WINS replication.

Doublecheck that the SERVERS are name resolution
clients NIC->IP properties -> Advanced

Report your precise errors for "cannot connect".
 
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