DNS problem with three DC's i different sites.

Discussion in 'DNS Server' started by Tom Eirik Jensen, Jun 1, 2010.

  1. Hi

    When I ping my domain name, I get an ip to a domian controller who is in a
    site i cannot reach. This answer somtimes is ok, but often the dns query
    fails, and I get the IP to a domain controller who is in a different site.
    I have defined IP subnets under site and services but this does not work.
    Are there any tip for me?

    When I ping my domain name, I assume that the DNS should return the IP of
    any domain controller who is in my site, according to my ipadress. Is that
    right ?
     
    Tom Eirik Jensen, Jun 1, 2010
    #1
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  2. Tom Eirik Jensen

    Chris Dent Guest

    No, not really.

    By default NetMask ordering is enabled and you will get a DC within the
    clients subnet if possible (matches on 255.255.255.0 by default, and
    will only match if the answer is within the client subnet). Otherwise
    standard round-robin ordering applies and the DC can be anywhere.

    However, that record is not used in such a simple manner for the most
    part. Instead Service Records are used to discover site-specific DCs if
    possible.

    What has prompted you to look at this?

    Chris
     
    Chris Dent, Jun 1, 2010
    #2
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  3. I am using DFS in the domain. \\domainName\dfsroot\share. Thought I could
    ping the domainName? And get answer from the nearest DC?
     
    Tom Eirik Jensen, Jun 1, 2010
    #3
  4. Tom Eirik Jensen

    Chris Dent Guest

    Not in pure DNS terms (with Ping), no. However, DFS service location is
    site-aware, the client will follow referrals returned by the DFS server
    and it will connect to a local or lowest cost DFS server if possible.

    If NetMask Ordering is either disabled or not applicable then
    continually running "nslookup domainName" should show round-robin
    rotation. This is DNS only though, it won't impact DFS server selection
    or logon server selection.

    Chris
     
    Chris Dent, Jun 1, 2010
    #4
  5. How can I test/use the DNS query for the nearest DC ? Which command can I
    use to test things like this?





     
    Tom Eirik Jensen, Jun 1, 2010
    #5
  6. Tom Eirik Jensen

    Chris Dent Guest

    You can look up the service record. e.g.:

    nslookup -q=srv _ldap._tcp.SiteName._sites.domainName
    Or:
    nslookup -q=srv _ldap._tcp.SiteName._sites.dc._msdcs.domainName

    However, while those are used for DC location they are not all that is
    used and they are not used for DFS server location.

    Chris
     
    Chris Dent, Jun 1, 2010
    #6
  7. Tom Eirik Jensen

    Chris Dent Guest

    Regarding testing for DFS, it's worth having a look at the DFSDiag
    utility, depending on the version (of Windows) you have you may be able
    to use the /TestReferral switch to check if and where clients will be
    redirected whenever they attempt to connect.

    Chris
     
    Chris Dent, Jun 1, 2010
    #7
  8. Thanks you for the help!


     
    Tom Eirik Jensen, Jun 1, 2010
    #8
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