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Wireless Networks Thread, Client can ping server but server cant ping client in Technical; Hi all, An interesting one for you today, hope someone can give me suggestions on what the problem might be. ...
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    Client can ping server but server cant ping client

    Hi all,

    An interesting one for you today, hope someone can give me suggestions on what the problem might be.

    I have a server 2008 R2 setup as DC. There are around 200 XP Pro clients with a couple of Windows 7 clients thrown in for good measure. I thought the network was ok as the clients can get onto the internet, access files on the server, run group policy etc etc as they should.

    At the moment I am researching shutting down the clients automatically and starting them up automatically. I have setup batch files to run the DOS command "shutdown /s /m \\pcname /t 90". As far as I was aware it was working fine except for the odd one which I presumed during testing was a problem with no network connection.

    After this happened a few more times and for nearly 50% of PCs in the latest computer lab I've tested I decided to investigate a bit further. As it turns out there is no network connection issue with the client as it can do all things it should be able to on the network (net, print, group policy, file access etc) and it can ping the server. However, when I try to ping the client from the server it returns with "the request timed out". If I try and ping each of the PCs with the problem from each other they get "request timed out" also but they can ping other clients that are not displaying the problem.

    The other thing is the shutdown batch files work by PC name not IP address (obviously as the IP changes) but the error I get back if I ping using the PC name can be either "request timed out" or interestingly "reply from IP addres of this PC: destination host unreachable". I have discovered that the IP address in the DHCP table and the IP address in the DNS table are different in the cae of the "destination host unreachable" so that would explain the error but why this happens in the first place is a wonder?

    If I turn off the PC, delete the entry in the DHCP table and reboot the PC then it will respond as normal to a ping from the server or a shutdown request.

    Can anyone help with this as to why a client cannot be pinged from the server even though it can ping the server and the server's entry for that PC in the DHCP table is correct. This seems to happen to at least 2 or 3 PCs in a computer lab.

    Thanks for any help you can give.

    K

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    Bezwick's Avatar
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    It sound to me like yopur DHCP server is not updateing your DNS server when it issues another IP address, hence it will work when you first create the machine but as the DNS & DHCP entries will be created at the same time. Have you checked the DHCP server to make sure it allows for dynamically updating the DNS entries?

    Sorry its on the DNS server, under lookup zone properties, "allow secure non sucure" dynamic updates.
    Last edited by Bezwick; 20th May 2011 at 12:54 PM.

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    KevWCFE (20th May 2011)

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    Thanks for the reply Bezwick,

    I have made that change, it had said "Secure Only". I restarted the DNS and DHCP services. Do you think the DNS issue is the reason for both problems or for just the ones where the IP in DNS and DHCP don't match?

    I picked on three PCs this morning that I knew weren't responding to the shutdown command or to pings. The third one is the only one where the DNS and DHCP entries were different but they all don't respond to a ping from the server. After doing what you suggested and restarting DNS and DHCP that third PC still has a different IP listed in the DNS table. Its timestamp says 06/12/2010.

    Should I (or can I) delete all the entries in the DNS table so that they refresh or is a restart going to update the DNS table?

    Thanks again for help on this.

    K

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    Bezwick's Avatar
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    From what i can gather they are both the same problem, restarting the DNS service and then leaving them overnight should resolve both issues.
    Good luck

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    KevWCFE (20th May 2011)

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    Thanks Bezz,

    I have scheduled the server to do a restart tonight at 10 when no one is here and I won't be back to check it out until Monday so that should be enough time to leave it.

    I'll let you know how I go...thanks.

    K

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    Sounds like you have stale entries for the clients in DNS. You need to enable scavenging on your DNS server to clear problems like this. If you Google DNS scavenging you will find a suitable guide. You must enable scavenging on the DNS server and the zone.

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    KevWCFE (20th May 2011)

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    Thanks ChrisH,

    I'll have a look at that and see if that will help. Sounds like a good plan.

    Cheers
    K

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