Random users drop connection to Exchange

[jmair]

I'm having an issue where some users (randomlly) dont have access to our mail server internally.

 

They are dynamic ips.

 

I have noticed that none of the static IP machines are having this issue.

also, if I go to the client machine directly, I'm able to run ipconfig /registerdns and it will resolve the problem (the client can ping all servers by name) for a random amount of time (an hour to a few days).

Any ideas what would be causing this?

[jmair]

I hate to shamelessly bump this, and I don't have much additional info to add however I would gladly give it to help troubleshoot this issue.

 

The additional info is: This issue isn't restricted to just the exchange server, it's also to our fileserver where users drives are mapped. Of course they can't connect to the Server, their mapped drive fails to connect. Also unable to ping the server by name, but I can by IP.

[matt40k]

What DNS servers are the DHCP servers giving out?

 

Are they the same as the static IPs?

 

They aren't different, ie different order?

[jmair]

What DNS servers are the DHCP servers giving out?

 

Are they the same as the static IPs?

 

They aren't different, ie different order?

Thanks for the quick reply.

 

I'm not sure what your asking exactly. So I'll answer the best i can.

The DNS and DHCP are on the same server. The scope is 10.1.1.x to 10.1.2.x.

I've checked the ip's on the client machines and they are within that scope.

[matt40k]

Generally, you have two DNS servers and two DHCP servers.

 

Are both DHCP servers giving out, for example

 

DNS1 10.1.1.1

DNS2 10.1.1.2

 

Or are they giving them out in any old order?

 

Basically do [start] [run] cmd [enter] ipconfig /all [enter] on a failed workstation

 

also do the same on a static workstation that works. See if you can spot any differences between the two (other then a different IP)?

 

Also, what is the IP of, say, the server? What is the IP of the failed workstation?

[jmair]

Generally, you have two DNS servers and two DHCP servers.

 

Are both DHCP servers giving out, for example

 

DNS1 10.1.1.1

DNS2 10.1.1.2

 

Or are they giving them out in any old order?

 

Basically do [start] [run] cmd [enter] ipconfig /all [enter] on a failed workstation

 

also do the same on a static workstation that works. See if you can spot any differences between the two (other then a different IP)?

 

Also, what is the IP of, say, the server? What is the IP of the failed workstation?

 

Only one DNS server giving out 10.1.1.2.

 

What's odd though is a machine that is effected won't have access to any number of servers. For example, it wont be able to get to exchange server by name or the DNS/DHCP server or the file server at random.

 

The next time it happens to a client machine I'll check if it grabbed a DNS ip from the dns server (I'm fairly sure it does though.)

[jmair]

Confirmed that the client machine gets the DNS address.

[bio]

How many domaincontrollers do you have and which of them are a Global Catalog ?

Perhaps you can use :

 

"c:\program files\microsoft office\office12\outlook.exe" /rpcdiag

 

it gives some additional how outlook connects to your exchange environment

 

regards

bio.

[jmair]

How many domaincontrollers do you have and which of them are a Global Catalog ?

Perhaps you can use :

 

"c:\program files\microsoft office\office12\outlook.exe" /rpcdiag

 

it gives some additional how outlook connects to your exchange environment

 

regards

bio.

 

We have one DC and it also holds the Global Catalog.

[jmair]

I just had a machine do the same issue (unable to connect or ping a server by name but it can by ip. And it's only to one random server, not all of them.)

 

I did an ipconfig /all

it gets a dns and ip.

 

I checked the DNS server and saw only one IP of 10.1.1.100 given to this machine and no other.

 

This seams to be totally random, any thoughts on even where to look for an answer?

[steve]

Try pinging the server with the -a command (ping x.x.x.x -a) from the problem PC.

 

This will resolve the name of the IP address.

 

If it gives the incorrect name then some thing's wrong with your DNS.

[steve]

From and ipconfig /all you'll get something like:

 

Windows IP Configuration

       Host Name . . . . . . . . . . . . : my-pc
       Primary Dns Suffix  . . . . . . . :
       Node Type . . . . . . . . . . . . : Unknown
       IP Routing Enabled. . . . . . . . : No
       WINS Proxy Enabled. . . . . . . . : No

Ethernet adapter Local Area Connection:

       Connection-specific DNS Suffix  . :
       Description . . . . . . . . . . . : Intel(R) PRO/1000 CT Network Connection
       Physical Address. . . . . . . . . : 00-0C-76-28-A9-5B
       Dhcp Enabled. . . . . . . . . . . : Yes
       Autoconfiguration Enabled . . . . : Yes
       IP Address. . . . . . . . . . . . : 192.168.1.14
       Subnet Mask . . . . . . . . . . . : 255.255.255.0
       Default Gateway . . . . . . . . . : 192.168.1.1
       DHCP Server . . . . . . . . . . . : 192.168.1.1
       DNS Servers . . . . . . . . . . . : 212.23.3.100
                                           212.23.6.100
       Lease Obtained. . . . . . . . . . : 09 April 2009 16:55:45
       Lease Expires . . . . . . . . . . : 12 April 2009 16:55:45

 

For this computer there are 2 DNS servers: 212.23.3.100, 212.23.6.100

 

Check on a dynamic assigned PC and a static assigned PC the DNS servers are the same as each other (they'll be different to mine).

 

Also check the DNS suffix on both PCs

[jmair]

From and ipconfig /all you'll get something like:

 

Windows IP Configuration

       Host Name . . . . . . . . . . . . : my-pc
       Primary Dns Suffix  . . . . . . . :
       Node Type . . . . . . . . . . . . : Unknown
       IP Routing Enabled. . . . . . . . : No
       WINS Proxy Enabled. . . . . . . . : No

Ethernet adapter Local Area Connection:

       Connection-specific DNS Suffix  . :
       Description . . . . . . . . . . . : Intel(R) PRO/1000 CT Network Connection
       Physical Address. . . . . . . . . : 00-0C-76-28-A9-5B
       Dhcp Enabled. . . . . . . . . . . : Yes
       Autoconfiguration Enabled . . . . : Yes
       IP Address. . . . . . . . . . . . : 192.168.1.14
       Subnet Mask . . . . . . . . . . . : 255.255.255.0
       Default Gateway . . . . . . . . . : 192.168.1.1
       DHCP Server . . . . . . . . . . . : 192.168.1.1
       DNS Servers . . . . . . . . . . . : 212.23.3.100
                                           212.23.6.100
       Lease Obtained. . . . . . . . . . : 09 April 2009 16:55:45
       Lease Expires . . . . . . . . . . : 12 April 2009 16:55:45

 

For this computer there are 2 DNS servers: 212.23.3.100, 212.23.6.100

 

Check on a dynamic assigned PC and a static assigned PC the DNS servers are the same as each other (they'll be different to mine).

 

Also check the DNS suffix on both PCs

 

Thanks for the quick reply.

 

Unfortunatly I've checked several times and the ipconfig /all looks fine. We only have one dns and it's been the same for all machine's i've checked. (It looks very much like mine, however mine is a static ip and hasn't had the problem.) What throws me off completely is that of the four machines on site, it will only not be able to resolve to one of those servers by name. It could be the exchange, or the fileserver or the webserver. It's random.

 

also if I do an nslookup, the return is our single dns server. looks fine there also.

Edited April 9, 2009 by jmair
needed to add nslookup comment.

[jmair]

well, i think i found the problem... I went back to that client machine and although it does have our DNS server as the primary DNS, there is also a second and third!....

Now i need to figure out how to get rid of those.

 

Thanks again.