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Netlogon problems?

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  • Netlogon problems?

    Hi All

    We currently have three domain controllers across our network, 2 reside on a class c subnet and 1 on a class b network and all are GC's.

    After noticing the load across the 2 class c servers going through the roof at peak login times, I checked the following:

    Class C Network
    C:\Documents and Settings\Administrator>nltest /server:s1 /logon_query
    Number of attempted logons: 1646
    The command completed successfully

    C:\Documents and Settings\Administrator>nltest /server:s2 /logon_query
    Number of attempted logons: 2699
    The command completed successfully

    Class B Network
    C:\Documents and Settings\Administrator>nltest /server:s6 /logon_query
    Number of attempted logons: 4
    The command completed successfully

    All machines across the Class B subnet are pointed to s6 for DNS, also after testing the domain via dcdiag all servers can replicate and are working together!!!

    But all logins would appear to go across the Class C network, or have I got this totally wrong and if so what would be the best way to test logon capabilites of the Class B server.

    Any advise would be great

  • #2
    Re: Netlogon problems?

    I may be barking up the wrong tree but take a look at the DNS SRV records' weight. It could be that there's an imbalance.
    Isolate Client Authentication Traffic from Exchange Facing Domain Controllers

    When clients authenticate, the DNS server returns a list of servers. In DNS, service (SRV) records have three values associated with them.

    For example, in DNS Manager, you would see an SRV record that looks similar to the following:

    _ldap._tcp._dc._msdcs.nwtraders.local [0] [100] [389] dc1.nwtraders.local

    The numeric values of the middle portion of this display are defined as follows:

    [0] represents the priority of the record. A client must attempt to contact the target host with the lowest-numbered priority it can reach. Target hosts with the same priority should be tried in an order defined by the weight of the record. The range is 0–65535.

    [100] represents the weight of the record. Weight determines how records of the same priority will be load balanced. The higher this value, the more likely the client will choose the domain controller identified in this SRV record against which to perform queries. Typically, weights are adjusted depending on the hardware platform of the domain controller. If there are two domain controllers, one with more processing power than the other, the more powerful domain controller can handle more query requests and thus should be given a greater percentage of the total workload.

    Note:Exchange Directory Access uses only the weight value to determine which server the client should prefer. Therefore, administrators can use the priority value to control Active Directory load generated by logons, and the weight value to control Active Directory load generated by Exchange. A higher weight results in a higher probability that Directory Access will choose a server. Directory Access treats a weight of 0 the same as it treats a weight of 1. If Directory Access cannot read the weight, it uses a default weight of 100.

    [389] represents the network port on which the service record will listen for activity.

    These values are controlled by the Net Logon service on the domain controller. Values of 0 for priority and 100 for weight are the default. Modify these values in the domain controller’s registry.
    Taken from
    Also see
    Both are not specific to the DNS but both go over it.

    Network Consultant/Engineer
    Baltimore - Washington area and beyond