Can't solve some hosts on client computers

Posted on 2010-01-07
Last Modified: 2012-05-08
We've got the problem that some hosts in the internet can't be solved by clientcomputers.
Generally is the solving quit slow from the clients.
If I try to surf to the homepage from the dc it is no problem.
I think there is a configuration error in dns or nic properties.
The network infastructure is as following:

Internet - Cablemodem - Firewall - DC (with is also DNS Server) - Clients
There is no proxy

Client Nic Settings:
Standardgateway: (Firewall)

DC Nic Settings:
Standardgateway: (FW)

Is there a facillity to export the dns settings in a file to post them?
We tried also with several browser

Question by:Opusretis
    LVL 11

    Expert Comment

    So let me understand your environment clearly. I won't add the 192.168 part which is the same for all network and call the IPs like 1.12.

    Is your firewall built in your cable modem (Is 1.10 also your modem)? Or are they seperate? Your DC is 1.12 but your DHCP server is 1.18, so is your DHCP server any other server in your environment? Or is 1.18 your cablemodem?

    I see that you forwarded your clients DNS requests to 1.12 which is your DC, and forwarded your DC to 1.10 which is your firewall. Where does your firewall forward these requests to (what is your firewall's DNS)?
    LVL 31

    Expert Comment

    by:Henrik Johansson
    All internal hosts shall use the internal DNS server on DC
    Incorrect to use FW as DNS on DC as FW is propably just forwarding the request to the external DNS server at the ISP.
    Configure the DC to use itself as DNS server and configure the DNS server properties' forwarders tab to forward unresolved queries to the external DNS server.
    Never use external/ISP addresses as DNS server on any internal host.

    Author Comment

    I refer to Answer one

    No the firewall is a sonicwall and not built in. The cablemodem is a normal modem without any router or firewall function.

    The DHCP 1.18 is a own windows server

    The Firewall gets his public IP from the ISP

    Author Comment

    I refer to Answer two from henjoh09

    How can I configure the DNS server properties' forwarders tab to forward unresolved queries to the external DNS server
    LVL 31

    Accepted Solution

    Use DNS MMC on the DC
    Right-click servername and choose Properties.
    Click Forwarders-tab
    In the 'DNS domain' list, 'All other domains' should be selected by default. You can if neaded add a specific domain for conditional forwarding so the specified domain is forwarded to the correct server (used when using trusts).
    Add the addresses that the DNS server shall forward to to the list.
    Close the dialog with ok-button

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