DNS Issue

Hi
I have stumbled upon a possible DNS issue (well I think it is)

Our Mac users here use Entourage to connect to exchange, just over the last couple of days I've had a random number of people report that they loose connection. Their entourage is setup to connect to the exchange box via its host name riverexch but it seems to be failing to connect using this method. If I enter the webmail address instead it connects fine. Also they are unable to connect to the Mac server using rivermacserv but can connect to it using it's IP address.

Can you please give me some indication of what I need to look for to resolve, assuming it's something on the domain controller that servers as DNS, DHCP etc.

Thanks
smiffy07Asked:
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vopCommented:
Does   ping riverexch   resolve the exchange server address correctly?

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smiffy07Author Commented:
no, on the machines affected it will not ping riverexch but will ping the IP address of the server
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carlmdCommented:
If you do nslookup of riverexch from one of the affected machines, does it show that it is using the correct dns server? You could compare the result to one that is working.

If it shows the correct dns server, can you ping it from the affected system? If not, run a traceroute and see where it is going bad.
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vopCommented:
Do the affected machines have the correct DNS address entered in tne network, TCP/IP properties?

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smiffy07Author Commented:
I'm just waiting for someone to report the issue once more, as soon as I find another affected machine I will run the tests above and report back.
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potato_bugCommented:
If the network adapters are set dynamic it could be that you have 2 DHCP servers on the domain and are allocating the wrong DNS servers after the lease time expires.

Verify that there are no routers on the network that have DHCP enabled or set DNS, Gateway and IP address static in the network configuration. Hopefully this may resolve.
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smiffy07Author Commented:
I'm not sure if it's connected but I have a new MacPro server running snow leopard server that had DNS running! I've stopped DNS on that machine now.
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carlmdCommented:
It should not be a problem to have multiple dns servers.

It is just a matter of which one you are pointing at.
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smiffy07Author Commented:
As far as I'm aware machines should be pointing to DC1 but will check when I find a machine that has been affected.
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smiffy07Author Commented:
I've just checked a few of the affected Macs relating to the problem raised here.

I have noticed on the network preference pane that they are picking up an old domain controller in the DNS section (as well as one of the current DC's)

I believe this to be the cause of the issue but unsure how to resolve, the DC in question has been inactive for over a year now and it was taken down due to a replication issue.

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carlmdCommented:
Remove it from the dns settings on each pc with the issue, or move the correct one to the top of the list.
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smiffy07Author Commented:
I'm pretty sure I tried that but will give it another go and report back.
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smiffy07Author Commented:
some of the old macs were picking up the old domain controller...added IP for new one and working fine now.
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