What is the difference between a forwarder and a conditional forwarder?

Discussion in 'DNS Server' started by Mikoyan, Dec 30, 2009.

  1. Mikoyan

    Mikoyan Guest

    In W2K3 exactly what is the difference between a forwarder and a conditional
    forwarder?

    Thanks Anastas
     
    Mikoyan, Dec 30, 2009
    #1
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  2. Hello Mikoyan,

    A conditional forwarder is according to the DNS domain name in the query.
    For example, a DNS server can be configured to forward all the queries it
    receives for names ending with widgets.example.com to the IP address of a
    specific DNS server or to the IP addresses of multiple DNS servers.

    From:
    http://technet.microsoft.com/en-us/library/cc782142(WS.10).aspx

    Best regards

    Meinolf Weber
     
    Meinolf Weber [MVP-DS], Dec 30, 2009
    #2
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  3. Mikoyan

    Mikoyan Guest

    Thanks for the reply Meinolf,

    So if I understand correctly, in the DNS server properties | Forwarders tab,
    if 'All other DNS domains' is selected then the DNS server is configured to
    *forward* requests to the IP address of a specific DNS server or to the IP
    addresses of multiple DNS servers; and if widgets.example.com is selected
    then it is configured to *conditionally* forward requests to the IP address
    of a specific DNS server or to the IP addresses of multiple DNS servers.
     
    Mikoyan, Dec 30, 2009
    #3
  4. In summary, that's correct. Conditional forwarding is normally used with
    partnership organizations. If you have a trust, for example, you can
    conditionally forward to the partner company's DNS server(s) for only their
    domain name, but create a general forwarder to the ISP's DNS for everything
    else.


    --
    Ace

    This posting is provided "AS-IS" with no warranties or guarantees and
    confers no rights.

    Please reply back to the newsgroup or forum for collaboration benefit among
    responding engineers, and to help others benefit from your resolution.

    Ace Fekay, MCT, MCITP EA, MCTS Windows 2008 & Exchange 2007, MCSE & MCSA
    2003/2000, MCSA Messaging 2003
    Microsoft Certified Trainer

    For urgent issues, please contact Microsoft PSS directly. Please check
    http://support.microsoft.com for regional support phone numbers.
     
    Ace Fekay [MCT], Dec 31, 2009
    #4
  5. Mikoyan

    Mikoyan Guest

    Thank you for the reply Jonathan,

    You mention stub zones in your reply.

    One would use a stub zone to enable a DNS server hosting a parent zone to
    remain aware of the authoritative DNS servers of one of its child zones. In
    contrast, a conditional forwarder would be useful in, for example, a company
    merger, allowing DNS clients in separate networks to resolve each others
    names without resorting to querying DNS servers on the Internet.

    Is my understanding correct?

    Best Regards, Anastas
     
    Mikoyan, Jan 7, 2010
    #5
  6. Just in case I misunderstood you, I apologize, but for a "DNS server hosting
    a parent zone to remain aware of the authoritative DNS servers of one of its
    child zones," is actually a parent-child delegation. Stubs are references
    for nameservers to other zones or namspaces, such as a partner
    organization's namespace or in a parent-child delegation. A stub actually
    pulls nameserver reference data as a zone transfer for only the SOA, NS, and
    glue A resource records returned in response to the query are stored in the
    stub zone. When a query comes in for that zone, the stub has the info for
    the nameservers of that namespace to resolve it.

    In many cases, Conditional Forwarding is used for a partner's namespace, but
    a stub can be used. Comparing the two, the advantage of the stub is that it
    can be stored in AD as Ad Integrated. This way, all DC/DNS servers in the
    replication scope will have a copy of the stub, whereas a Conditional
    Forwarder must be created manually on each DNS server. That can be one
    drawback, however if the security model of an org states that only one DNS
    server will communicate outside, then forwarding from all DNS server will be
    pointed to this one DNS server, which then can have a stub or conditional or
    general forwarder going outside (whether to the internet or partner).

    More info:

    Understanding stub zones: Domain Name System(DNS)Jan 21, 2005 ... A stub
    zone is a copy of a zone that contains only those resource records necessary
    to identify the authoritative Domain Name System (DNS) ...
    http://technet.microsoft.com/en-us/library/cc779197(WS.10).aspx

    Using stub zones: Domain Name System(DNS)Jan 21, 2005 ... Keep delegated
    zone information current. By updating a stub zone for one of its child zones
    regularly, the DNS server hosting both the ...
    http://technet.microsoft.com/en-us/library/cc775397(WS.10).aspx

    Ace
     
    Ace Fekay [MVP-DS, MCT], Jan 7, 2010
    #6
  7. Mikoyan

    Mikoyan Guest

    Thanks Ace for the reply,

    No apology needed at all, my confusion was in no way due to any of your
    explanations, but originated from here:

    http://technet.microsoft.com/en-us/library/cc780434(WS.10).aspx

    Specifically:

    "Stub zones are used when you want a DNS server hosting a parent zone to
    remain aware of the authoritative DNS servers for one of its child zones. If
    the stub zone for a child zone is hosted on the same DNS server as the
    parent zone, the DNS server hosting the stub zone will receive a list of all
    new authoritative DNS servers for the child zone when it requests an update
    from the stub zone's master server . This method of updating the DNS server
    hosting the parent zone maintains a current list of the authoritative DNS
    servers for the child zone as they are added and removed."

    However, as the links you provide clearly state, Stub zones are for more
    than just parent and child zone resolution, but can also be used for
    separate DNS namespaces.

    Best Regards, Anastas
     
    Mikoyan, Jan 7, 2010
    #7


  8. Hi Anastas,

    Yes, that's correct. The article you mentioned gives only a portion of a
    stub's possible uses.

    Cheers!

    Ace
     
    Ace Fekay [MVP-DS, MCT], Jan 7, 2010
    #8
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