Sever set to static IP in DNS on Domain controller, put into DHPC

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Guest

We have two severs set as Domain Controllers. On both machines, our exchange
server is in the DNS settings with the correct IP address. Each morning this
week, when I come in, one Domain controller (the same each time) has added
the Exchange server to DHPC. The other domain controller continues to see
the server with the correct IP address.
What would cause this, and what can I do to aleviate this?
 
Kevin Powell said:
We have two severs set as Domain Controllers. On both machines, our exchange
server is in the DNS settings with the correct IP address. Each morning this
week, when I come in, one Domain controller (the same each time) has added
the Exchange server to DHPC.
Click to expand...

What does the above "added Exchange server to DHCP"
even mean?

A DHCP assigned address is ONLY possible if NIC on the
machine is set to 'obtain IP automatically'.

DCs have nothing to do with such DHCP settings, and pratically
nothing to do with DHCP at all ('authorization' is the exception.)
The other domain controller continues to see
the server with the correct IP address.
Click to expand...

"See" probably means that the DNS records are correct
for the DC -- and that no OTHER machine is being assigned
the address (either manually or by DHCP server. )
What would cause this, and what can I do to aleviate this?
Click to expand...

What exactly are you seeing, and in what tool?
 
Sorry, I should preface by saying I am not the network admin. But he is
stumped, and I am the one dealing with it first thing in the morning. Please
be patient.

:


What does the above "added Exchange server to DHCP"
even mean?

A DHCP assigned address is ONLY possible if NIC on the
machine is set to 'obtain IP automatically'.

DCs have nothing to do with such DHCP settings, and pratically
nothing to do with DHCP at all ('authorization' is the exception.)

"See" probably means that the DNS records are correct
for the DC -- and that no OTHER machine is being assigned
the address (either manually or by DHCP server. )

What exactly are you seeing, and in what tool?
Click to expand...
Ok, if I go on either DC and use the DNS tool under the administrative
tools, I see our mail server is assinged the correct IP. But, on one DC,
under the DHCP tool the mail server is listed with a different IP address.
If I go into CMD and ping the server name, one DC pings the correct address,
the other user the incorrect address (the one it has listed in the DHCP tool).
If I go into the DHCP tool and delete the entry for the mail server,
everthing works fine. But the next morning, that same DC will have it listed
as DHCP again.
This causes any user who logs in and is authenticated to the DC with the
problem to not be able to connect to the mail sever. If I ping from one of
these users machines, it tries to ping the wrong IP.
I realize there may be a whole slew of problems with out network setup. But
I can only deal with what I have been given.
 
Kevin Powell said:
Sorry, I should preface by saying I am not the network admin. But he is
stumped, and I am the one dealing with it first thing in the morning. Please
be patient.
Click to expand...

Not a problem, other than that to help you we will
have to understand you problem and may need to
ask you very precise questions or ask that you
provide very precise (or accurate) answers.
Ok, if I go on either DC and use the DNS tool under the administrative
tools, I see our mail server is assinged the correct IP. But, on one DC,
under the DHCP tool the mail server is listed with a different IP address.
Click to expand...

Ok, so are you saying that in DHCP there is a lease
that gives the name of the email server?

Go to the email server and see if it is receiving
an address from DHCP, by typing:

ipconfig /all

If it receives a DHCP address (for any NIC) then
the DHCP server, the lease expiration, etc. will
be listed on that NIC.

If not, then the entry in DHCP is left over from the
past or somehow erronenous and likely irrelevant.
If I go into CMD and ping the server name, one DC pings the correct address,
the other user the incorrect address (the one it has listed in the DHCP
Click to expand...
tool).

Ok, then that implies that the email server is somehow
not only assigned the address but also has registered it
in DNS which IS RELEVANT.

Does the ping work in both cases, or just in one (or none)?

Does the email server have TWO NICs?

My (working) guess is that you have two NICs and
the "extra" (or wrong) one is also getting registered.

That can be prevented by unchecking the register this
interface on the NIC->IP->Advanced->DNS tab.
OR by giving it another name if you wish it to register
but be distinguished (e.g., I register the OUTER NICs
of my Proxy server with an extra "cable" or "dsl"
subdomain name to distinguish them: x.cable.domain.com

If I go into the DHCP tool and delete the entry for the mail server,
everthing works fine.
Click to expand...

Deleting the entry in DHCP should change NOTHING
about the machine -- the computer THINKS it still owns
the address until the lease expires so that makes little
sense.
But the next morning, that same DC will have it listed
as DHCP again.
Click to expand...

Likely it renews the address.
This causes any user who logs in and is authenticated to the DC with the
problem to not be able to connect to the mail sever.
Click to expand...

Actually that isn't really the case -- the authentication and
the name resolution are completely separate -- it is just
likely that those using this DC also use the same MACHINE
as a DNS server (it's an accident of circumstances not of the
authentication.)
If I ping from one of
these users machines, it tries to ping the wrong IP.
Click to expand...

Does it work? Or fail?

Is that address being use on the email server?

If not, then likely there is ANOTHER MACHINE
out there with the same name that is getting itself
confused with the email server.
I realize there may be a whole slew of problems with out network setup. But
I can only deal with what I have been given.
Click to expand...

Understood, but we will have to help you find out
enough to actually fix it without making it worse or
flailing around with things that don't matter (and thus
confusing the issue more.)
 
You're being a great help Herb.

Quick question, as I can;t get to the server room currently. We just
recently put in a new Cisco router. This is when the problem started. I
don't know why I didn't mention it, as I have wondered from the start if this
caused it.

I will try to get futher info for you when I can.
 
In
Kevin Powell said:
Ok, if I go on either DC and use the DNS tool under the
administrative
tools, I see our mail server is assinged the correct IP.
But, on one DC, under the DHCP tool the mail server is
listed with a different IP address.
If I go into CMD and ping the server name, one DC pings
the correct address, the other user the incorrect address
(the one it has listed in the DHCP tool). If I go into
the DHCP tool and delete the entry for the mail server,
everthing works fine. But the next morning, that same DC
will have it listed as DHCP again.
This causes any user who logs in and is authenticated to
the DC with the problem to not be able to connect to the
mail sever. If I ping from one of these users machines,
it tries to ping the wrong IP.
I realize there may be a whole slew of problems with out
network setup. But I can only deal with what I have been
given.
Click to expand...

Does the problem DC have Remote Access Service so clients can VPN or dial
into it?

That is the behavior you'll see on a RAS server, if it is a RAS server needs
some extra configuration to prevent communication problems.
292822 - Name resolution and connectivity issues on a Routing and Remote
Access Server that also runs DNS or WINS:
http://support.microsoft.com/default.aspx?scid=kb;en-us;Q292822
 
Kevin Powell said:
You're being a great help Herb.

Quick question, as I can;t get to the server room currently. We just
recently put in a new Cisco router. This is when the problem started. I
don't know why I didn't mention it, as I have wondered from the start if this
caused it.
Click to expand...

That isn't going to affect the DHCP server you have,
in the way you describe.

It might STOP a DC from giving out an address, or
if it has a DHCP server it might interfere by giving
out a different IP address.
 
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