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Thread: Windows 2008 DNS? Very slow internet

  1. #1
    dor Guest

    Windows 2008 DNS? Very slow internet

    We just installed a completely new Windows 2008 domain with 2 servers,
    one running DNS. Everything is working great except the internet.
    The pages come up but its soooo slow to load the pages. We checked
    with ISP and all speeds are above normal.
    What could be causing this…internal DNS problem?
    We have DHCP enabled for all clients with the servers IP address being
    handed out for DNS. The server is using itself for DNS and has all
    static IP info in.
    Any help would really be appreciated!!

  2. #2
    Bill Grant Guest

    Re: Windows 2008 DNS? Very slow internet

    No, it won't be DNS. DNS just resolves the URL to an IP. Once the client
    machine has the IP address to connect to, DNS has no further part in it.

  3. #3
    dor Guest

    Re: Windows 2008 DNS? Very slow internet

    What about a DNS forwarder to ISP DNS?
    Is there a doc out there with how Windows 2008 DNS should be setup?

  4. #4
    Ace Fekay [MCT] Guest

    Re: Windows 2008 DNS? Very slow internet

    I agree with Bill that DNS is not causing this, whether you setup a
    Forwarder or not, but a Forwarder is recommended to offload resolution
    processing to the ISP's DNS server.

    As for the "slowness," that can be defined multiple ways and depends on your
    setup. Describe your setup, such as do you have ADSL and the 2008 machine
    has two NICs and is the NAT device, or is there a router and the 2008 has
    one NIC, etc. Be descriptive, please. Also, is 2008 a DC?

    Also post an ipconfig /all from the 2008 machine so we can evaluate the
    config and make suggestions if necessary.

  5. #5
    Rudolf Meier Guest
    You have to correct the setting for the dns forewarding. Alltough it should
    not have such an influence (as mentioned by Bill and Ace) it still has...
    the resolution is extremely slow, because your server always starts at the
    root servers for every resolution. (we had the same problem after replacing
    our dns server) ...

    Often in the process of deploying a new server and DNS in an existing
    environment, a bad DNS FORWARDER record gets left behind in your new DNS
    server. The problem doesn't present itself until you decomission the old DNS
    server. Your new DNS server is very slow with external DNS lookups because
    it forwards requests to a DNS server that no longer exists. This process
    eventually falls and finds and alternate DNS path for resolution.

    To correct this problem look for and remove the "dead DNS forwarder" records
    from your new DNS server.

    Open the DNS manager,
    right click on the DNS server and choose properties,
    select the FORWARDERS tab,
    remove and invalid DNS server forwarder records.

    Resolution should be immediate without restart.

  6. #6
    Ace Fekay [MCT] Guest

    Re: Windows 2008 DNS? Very slow internet

    I wouldn't exactly put it that way. And I wouldn't call it a 'dead'
    forwarder. It may not necessarily manifest itself when decommissioning a
    server, rather it can manifest itself at any time.

    If a DNS server that is set as a Forwarder is no longer functioning, or if
    whomever owns the server decides to disable Recursion, which will make it
    not respond to queries to zones it does not host (effectively making it a
    content only server), or is controlling it by "views" ( a BIND feature to
    control what subnets it responds to for queries), then the DNS service will
    follow a time-out (TTL or Time to Live) algorithm when it sends the query to
    the first Forwarder in the list. If there is no response (NULL response)
    after the TTL, then it eliminate that Forwarder for this query only, and it
    will then send the query to the next Forwarder in the list. If none of the
    Forwarders respond, the DNS service will then send the query to the Root
    Hints to devolve the query.

    Now - and this is an important "now," if there are many DNS servers listed
    in the Forwarders list, such as 3 or 4, the time out value for the number of
    Forwarders listed may exceed the timeout (TTL) the client side resolver
    service is set to by default (on the client machine making the request),
    therefore receiving that familiar 'HTTP 404 not found' in the browser.

    For practical purposes understanding the TTLs, I would suggest to never set
    more than two Forwarders.

    To find out if a DNS server will respond to queries and be eligible to be
    used as a Forwarder, you can test it by using the nslookup utility (use
    set -d2 option and look for 'recursion available' or 'recursion not
    available'

  7. #7
    Join Date
    Apr 2010
    Posts
    1

    Re: Windows 2008 DNS? Very slow internet

    I have a similar problem. I have a Server 2008 Enterprise, internet router is connected directly tothe server and distributes to the network via routinga and remote acess. On ther server, speed tests display internet download at around 80MB, but on the network clients, it won't go faster than 9MB. What could it be?

  8. #8
    Join Date
    May 2012
    Posts
    1

    Re: Windows 2008 DNS? Very slow internet

    Quote Originally Posted by Rudolf Meier View Post
    You have to correct the setting for the dns forewarding. Alltough it should
    not have such an influence (as mentioned by Bill and Ace) it still has...
    the resolution is extremely slow, because your server always starts at the
    root servers for every resolution. (we had the same problem after replacing
    our dns server) ...

    Often in the process of deploying a new server and DNS in an existing
    environment, a bad DNS FORWARDER record gets left behind in your new DNS
    server. The problem doesn't present itself until you decomission the old DNS
    server. Your new DNS server is very slow with external DNS lookups because
    it forwards requests to a DNS server that no longer exists. This process
    eventually falls and finds and alternate DNS path for resolution.

    To correct this problem look for and remove the "dead DNS forwarder" records
    from your new DNS server.

    Open the DNS manager,
    right click on the DNS server and choose properties,
    select the FORWARDERS tab,
    remove and invalid DNS server forwarder records.

    Resolution should be immediate without restart.
    While this wasn't the exact thing that was happening with me, i was having a similar problem.
    I set the DC/DNS server up at home, and it automatically pulled in my gateway as the forwarder address. When i brought this into the office it was looking for the old (10.0.0.138) gateway which obviously could not be found. I deleted this entry and everything began to run smoothly once again.
    I would like you to know that i registered on this site just to say thank you!

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