DNS is VERY slow...

Posted on 2007-07-25
Last Modified: 2010-05-18
We installed SBS 2003 in the office a few months ago.

Since then, Internet browsing is very slow. It's not a connection speed issue, because downloads a quick enough. The problem seems to be in resoving the DNS info.

I don't have a complete understanding of the DNS process. But I would prefer to use the DNS of my ISP instead of maintaining an internal DNS (which I don't know how to do).

As a test, I set the DNS of one of the client computers to the ISP's DNS and the browsing picked up speed immediately, but then it cause problems with logging on to the domain. It worked, but took forever.

Any help would be greatly appreciated!

Question by:scend
    LVL 77

    Accepted Solution

    Because you are using SBS you must use the CEICW) (Configure E-mail and Internet Conection Wizard - located server management | Internet and E-mail | connect to the Internet) to set up DNS. However to review you can look in the various consoles to see if it is configured properly. DNS MUST be handled by only your internal DNS server, the SBS, and Internet requests are send to your ISP through forwarders. Sounds like your forwarders may not be added or configured correctly. Please review the following and let us know what further information your need:

    Assuming you have completed the server installation, installed Active Directory, and joined the workstations to the Domain, make sure DNS is configured as follows, assuming a single network adapter:
    -The server's NIC should be configured with a static IP, the Internet router as the gateway, and only the server itself as the DNS server. Do not use an ISP DNS server here. If using 2 NIC's the internal NIC does not get a gateway assigned, and uses the server itself again for DNS.
    -Each workstation should be configured using DHCP (obtain and IP address and DNS automatically) or if configured with static addresses; a static IP in the same subnet as the server, same subnet mask as the server, the gateway pointing to your Internet router, and the DNS server pointing ONLY to the server/domain controller. Again do not put an ISP's DNS server here
    -In the DNS management console under Administrative tools, right click on the server name and choose properties. On the Forwarders tab add your ISP's DNS servers
    -If the workstations are using DHCP, open the DHCP management console on the server under Administrative tools and click on the server name to expand it, click on the scope to expand it, right click on scope options and choose configure options. On the general tab add the Internet router's IP in #003 router, the server's IP in #006 DNS Servers, and the domain name and suffix under #015 such as mydomain.local
    -If  DHCP is enabled on the router, rather than the server, it should really be disabled on the router and configured on the server. Enabling DHCP on the server assists with dynamic updates to DNS for older clients, allows for central management, and far more scope options.
    -The DHCP client service should be running on servers and workstations even where you are not using DHCP assignments. The DHCP client service controls the dynamic DNS updates
    If you have been having DNS problems, on the workstations that have been having problems you should clear the DNS cache by entering at a command line  
      ipconfig  /flushdns
    and then
      ipconfig  /registerdns
    This should help with the slow logons. If you have the ISP's DNS's anywhere in the NIC's, the workstations will often go to the Internet to try to resolve names and cause them to "hang".

    Author Comment

    Wow! I've been fighting with this problem for a year and nobody ever gave me a solution that worked. Turned out the one of the IP addesses in my forwarders was typed incorrectly -- so it tried to resolve that first, then went on the #2. That caused the lag.

    I didn't even know how to get into the forwarders to check. Thanks for the help!
    LVL 77

    Expert Comment

    by:Rob Williams
    Very welcome, glad it was of some help.
    Cheers !

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