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Round Robin is killing performance on our network RRS feed

  • Question

  • We had two Windows 2003 Domain Controllers at our data center with DNS and one domain controller at our large remote office with no DNS. We just finished replacing all three domain controllers with Windows 2012 R2 DC's, each of which have DNS installed and configured. We're having issues with servers at our data center occasionally resolving names using the DNS server at the remote office due to what appears to be round robin DNS lookups.

    Is there a suggested way to force servers and workstations at the data center to only use the domain controllers at that location for DNS resolution and the servers and workstations at the remote office to only use the domain controller at that location for DNS resolution?

    Thanks in advance for any assistance,

    Dan


    Thursday, March 3, 2016 2:49 AM

Answers

  • Hi dbetanco,

    >We're having issues with servers at our data center occasionally resolving names using the DNS server at the remote office due to what appears to be round robin DNS lookups.

    Round robin is for specific record query, for example, in DNS zone has three records:

    www.test.com A 1.1.1.1

    www.test.com A 2.2.2.2

    www.test.com A 3.3.3.3

    Then if we query nslookup www.test.com three times,

    First time the order is:

    1.1.1.1; 2.2.2.2; 3.3.3.3;

    Second time the order is:

    2.2.2.2; 3.3.3.3; 1.1.1.1;

    Third time the order is:

    3.3.3.3; 1.1.1.1; 2.2.2.2

    As we generally use the first IP, so we may use different IP address to visit www.test.com each time.

    >Is there a suggested way to force servers and workstations at the data center to only use the domain controllers at that location for DNS resolution and the servers and workstations at the remote office to only use the domain controller at that location for DNS resolution?

    To specific DNS server address, we need to check the preferred DNS server address configured in client's TCP/IP properties. Check if the address is the DNS server's address that you want to use.

    If the clients get IP configurations from DHCP server, then you may check DHCP option 006.

    Besides, round robin can be disable:

    Best Regards,

    Anne


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    Thursday, March 3, 2016 7:10 AM
    Moderator

All replies

  • Hi dbetanco,

    >We're having issues with servers at our data center occasionally resolving names using the DNS server at the remote office due to what appears to be round robin DNS lookups.

    Round robin is for specific record query, for example, in DNS zone has three records:

    www.test.com A 1.1.1.1

    www.test.com A 2.2.2.2

    www.test.com A 3.3.3.3

    Then if we query nslookup www.test.com three times,

    First time the order is:

    1.1.1.1; 2.2.2.2; 3.3.3.3;

    Second time the order is:

    2.2.2.2; 3.3.3.3; 1.1.1.1;

    Third time the order is:

    3.3.3.3; 1.1.1.1; 2.2.2.2

    As we generally use the first IP, so we may use different IP address to visit www.test.com each time.

    >Is there a suggested way to force servers and workstations at the data center to only use the domain controllers at that location for DNS resolution and the servers and workstations at the remote office to only use the domain controller at that location for DNS resolution?

    To specific DNS server address, we need to check the preferred DNS server address configured in client's TCP/IP properties. Check if the address is the DNS server's address that you want to use.

    If the clients get IP configurations from DHCP server, then you may check DHCP option 006.

    Besides, round robin can be disable:

    Best Regards,

    Anne


    Please remember to mark the replies as answers if they help and unmark them if they provide no help. If you have feedback for TechNet Support, contact tnmff@microsoft.com.


    Thursday, March 3, 2016 7:10 AM
    Moderator
  • configure the NIC to use one IP address for DNS lookups on the server?
    • Proposed as answer by cguan Thursday, March 3, 2016 9:38 AM
    Thursday, March 3, 2016 7:59 AM
  • Hi Jon.Knight,

    Yes.

    If you both configure "preferred DNS server" and "Alternate DNS server". Then if the client can't connect with the preferred DNS server, it will turn to query the Alternate DNS server.

    Best Regards,

    Anne


    Please remember to mark the replies as answers if they help and unmark them if they provide no help. If you have feedback for TechNet Support, contact tnmff@microsoft.com.

    Thursday, March 3, 2016 8:03 AM
    Moderator
  • I'm starting to think this may not just be a DNS issue as all of our servers and clients are configured with the primary/secondary DNS pointing to the DC/DNS servers at the Data Center

    It looks like the zone (DomainName.com) that AD is located on is what is returning different ping results and rotating from DC to DC to DC. This of course is affecting when LDAP and similar lookups are performed that use the zone name.

    I'm not sure how to get server lookups to DomainName.com to only resolve to DC1 & DC2 located at the data center from servers & workstations at the data center.

    Thanks for ALL the responses so far and for any future assistance,

    Dan

    Thursday, March 3, 2016 12:05 PM
  • Do you have the two locations defined as separate AD sites?

    what is doing the LDAP lookups? can you hardcode the DC into the query?

    Thursday, March 3, 2016 3:42 PM
  • Hi dbetanco,

    I have a question, how do you know that clients in site1 which configure "preferred DNS" with DNS1 use DNS2 in site2 to resolve? (site1: data center; site2: remote office)

    And I noticed you say this issue occurs "occasionally".

    I think we need to use network monitor to see the detailed process of the DNS resolution:

    Network monitor download:

    https://www.microsoft.com/en-us/download/details.aspx?id=4865

    Use command nslookup in cmd, and install network monitor both on clients and DNS server, in Network monitor, set filter with "dns", then we may see the detailed process.

    Best Regards,

    Anne


    Please remember to mark the replies as answers if they help and unmark them if they provide no help. If you have feedback for TechNet Support, contact tnmff@microsoft.com.

    Friday, March 4, 2016 1:47 AM
    Moderator