Slow SQL Connection or Network in Windows 7 – Update

Finally found a small problem with Windows 7.  After upgrading, we have discovered that Windows 7 was responding slow to our SQL Server 2005.  What we discovered is below.

Slow response times in Windows 7 to a SQL Server can be due to the LLMNR protocol.  This may be resolved by turning off the LLMNR protocol.

LLMNR is a protocol that allows both IPv6/4 computers to perform name resolution for the NetBIOS names of other computers without requiring a DNS server.

IPv4 hosts can use NetBIOS over TCP/IP (NetBT) to resolve computer names to IPv4 addresses for neighboring computers by broadcasting a NetBIOS Query.

All IPv4-based LLMNR hosts listen on the IPv4 multicast address 224.0.0.252 instruct their Ethernet network adapters to listen for Ethernet frames with a destination multicast address.

Windows Vista and 7-based LLMNR computers do not send or respond to unicast queries.

To disable LLMNR:

Modify Group Policy – Go to Search – Type GPEdit.msc – Enter – Navigate to the following and make sure Enabled is checked -


Computer Configuration\Administrative Templates\Network\DNS Client
\Turn off Multicast Name Resolution = Enabled

How does Multicasting Work?  Here’s a good explanation

Update -

LLMNR

Windows Vista and Windows Server “Longhorn” support Link-Local Multicast Name Resolution (LLMNR), which allows IPv6 hosts on a single subnet without a DNS server to resolve each other’s names. This capability is useful for single-subnet home networks and ad hoc wireless networks. Rather than unicasting a DNS query to a DNS server, LLMNR nodes send their DNS queries to a multicast address on which all the LLMNR-capable nodes of the subnet are listening. The owner of the queried name sends a unicast response. IPv4 nodes can also use LLMNR to perform local subnet name resolution without having to rely on NetBIOS over TCP/IP broadcasts.

Dawn M. Babian, GSAE
Instructor

Disabling LLMNR (Below)

Professional or Enterprise (Gpedit.msc)

Home Edition

Create a registry key as follows -

You also should go to your network adapter properties and disable all of the settings under the advanced properties such as TCP/Offload and other advanced settings.  Remember, not all adapters have advanced options – disable any settings that allow you to do so….

Disable your anti-virus and check the speed.  Is your anti-virus causing issues?

See our article -

Phrases you may hear in IT

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13 Responses to Slow SQL Connection or Network in Windows 7 – Update

  1. Rafael Guedes says:

    Thanks!

    I didn’t get LLMNR disabled until I read your post. I’m using W2K8 R2 and I already have tryed disable it through registry, but I could via GP.

    Cheers.

  2. Antonella Mattioli says:

    Thank you!!!!!

  3. Cork Shunk says:

    This made a hugh difference in performance on a new Win 7 (32)bit PC I hooked up to my Office P2P yesterday. I am not an It professional but I have several Clients who are disappointed with the performance of their new Windows 7 PCs vs the old XP Pcs they replaced. Most of these are on Domains with new Win 2008 server so I don’t know if this will help but I will be fowarding this link to their IT people.

    Thanks,
    Cork Shunk
    CS-Graphx

  4. Daryn O'Shea says:

    You rock. This totally fixed my issue… so tough to find. I had found suggestions to install SQL Native Client v10.0 and to use named pipes instead of TCP, but I see that these solutions had negligible impact (well, I haven’t actually set up the named pipes yet but will try that later). Simply turning off this protocol immediately returned to a useful state my Microsoft Access to ODBC application running on Vista and on a Windows 7 client that we are just now setting up. Interestingly, the Windows 7 client is slower, but the processor is much less than the one on the Vista machine. Huge difference on both machines, though. Yay!

    Also note that we have had to manually assign IPv4 addresses and DNS server addresses to these machines. When allowing our DLink router to assign them through DHCP, something completely blocked our ability to connect to the SQL servers. I did notice that when using DHCP a DNS suffix was assigned when viewing “ipconfig /all”, whereas there is no suffix when it is manually assigned. Trust me, this one made me pull my hair out; very frustrating.

    • We had the same problem and Dawn Babian, our IT specialist and myself had to reverse engineer and read some very boring stuff before we found LLMNR and the other settings. You also should go to your network adapter properties and disable all of the settings under the advanced properties such as TCP/Offload and other advanced settings. Remember, not all adapters have advanced options – disable any settings that allow you to do so….you will see a difference in your SQL response.

  5. Pingback: Memory in SQL « TTC Shelbyville – Technical Blog

  6. Munna Singh says:

    Still if you are facing the issue, please see blow resolution:
    Root Cause
    ——————————————————————-
    The issue which we were seeing on Win7 VDIs could be due to the Network hardware device connected with the machine. If TCP/IP scaling is not supported by the network device then the performance will be slow.

    Solution
    ——————————————————————-
    Disable auto tuning level of the TCP. Please follow below steps:
    1) Open command Prompt with admin right (Run as Admin)
    2) Type “netsh interface tcp set global autotuninglevel=disabled”
    3) After running above command restart the machine.

    For other information on this command, visit link “http://support.microsoft.com/kb/935400”

  7. Pingback: Slow SQL or Network Connection - Windows 7 / Server 2008 | Dynamic Tech Blog

  8. Cork Shunk says:

    Recently got a Dell latitude with windows 8 Pro and although file server performance with MS Access backend db on P2P network was fine the connection to a backend db on SQL Server 2008R2 located on a Windows 7 Pro PC was very slow, opening a record took 2-3 seconds. Linking to the SQL db with DNS less connection took 30-45 seconds. This did the trick, improved SQL Server performance more than 100%. Opening records is now instantaneous. Linking to SQL db now takes 3 seconds.

    Thanks again
    Cork Shunk
    CS-Graphx

  9. Tomas Moh says:

    Thank you. It works like a charm.

  10. Kevin Miller says:

    Thank you so much for taking the time to put this on the internet. I read dozens of threads before I found this. This solved my problem in a dramatic way.

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