DNS Subdomain Vs Delegation

Discussion in 'MCSA' started by pennino, Apr 20, 2005.

  1. pennino

    pennino Guest


    can anybody tell me what is the difference between
    creating a subdomain or a delegation to a primary zone on
    the same server ? What I mean is:

    domain: example.com on server1 (primary zone)

    1) create subdomain "dev.example.com" on server1.
    2) create new primary zone "dev.example.com" on server1.
    Create delegation under "example.com" on server1 that
    points to itself. (windows does this automatically if I
    create a new zone that has the same root domain as a
    primary zone)

    As far as I understand, the only difference is that in
    the second example I can replicate the domain and the
    subdomain independently when using standard zone
    transfers. What do you usually do in a production
    environent ?

    Thank you.
    pennino, Apr 20, 2005
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  2. pennino

    catwalker63 Guest

    The delegation option is for moving the subdomain zone to a different
    server and/or location. This way you can also delegate administration of
    the zone. An example would be where you had several subdomains in
    different locations where each has its own DNS adminstrator.

    aka Pu$$y Feet
    MCNGP #43
    "If man could be crossed with the cat, it would improve man, but it would
    deteriorate the cat." Mark Twain
    catwalker63, Apr 20, 2005
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  3. pennino

    pennino Guest


    Yes, I understand that. But I was talking about a single
    DNS server. Let's say you have to create a subdomain on
    your "example.com" domain, called "dev" (so,
    dev.example.com"). You don't plan, for the moment, to
    create a separate DNS server to host the subdomain. So
    you create a "real" subdomain on the main DNS server and
    start populating it. Then, after some time, you create a
    second DNS server and decide that it would be better to
    host "dev.example.com" on that server. If I understand
    correctly, now you have to drop your subdomain on the
    first DNS server, create the subdomain from scratch on
    server2 and delegate it from server1.

    Now, if you had created a delegation to itself in the
    first place, all you would have to do would be to create
    a secondary zone on server2, transfer
    the "dev.example.com" from server1, change the delegation
    for "dev.example.com" from server1 to server2, change the
    zone on server2 from secondary to primary and
    delete "dev.example.com" from server1. Without having to
    recreate any RRs.

    So if my assumption is correct, then it would make sense
    to always create a subdomain as a separate zone and
    delegate to itself instead of creating a physical
    subdomain under the parent.

    Is that correct ?

    pennino, Apr 21, 2005
  4. pennino

    catwalker63 Guest

    "pennino" <> prattled ceaslessly in

    No. If the zone is hosted on the same server, you do not delegate.
    Since it is a contiguous namespace, it will not work properly unless it
    is either a part of the zone on the one server or delegated to another
    separate server. Give it a try in a test environment.

    aka Pu$$y Feet
    MCNGP #43
    "If man could be crossed with the cat, it would improve man, but it would
    deteriorate the cat." Mark Twain
    catwalker63, Apr 21, 2005
  5. pennino

    Kurt Hudson Guest

    In a production environment you would simply create a
    subdomain without delegation. The only exception that I
    have ever seen, one that Microsoft implemented in Server
    2003, is the automatic local delegation of the _MSDCS
    namespace. They did that because there was a problem when
    domain controllers in other domains in a forest would try
    to get updates about all the domain controllers in the
    forest using the server type or by GUID.

    Check out this link for some additional detail on DNS,
    delegation, and secondary zones in Windows Server 2003

    Kurt Hudson, Apr 22, 2005
  6. pennino

    pennino Guest

    I did. What do you mean by not working properly ? Before
    asking my original question I had already tried both
    implementations (subdomain vs delegation on same server)
    and both work fine. That's why I asked what you do in a
    production system. Actually, if you create a new zone on
    a server where a parent zone already exists, the DNS
    server automagically does the local delegation for you.
    Also, as Kurt pointed out, the _MSDCS is another such
    example. I read the document Kurt referenced but it just
    explains delegation in the classic role (hosting a
    subomain on a different server).
    pennino, Apr 23, 2005
  7. pennino


    Jun 30, 2013
    Likes Received:
    You don't even need to create any delegation as the two zones(dev.example.com and example.com) are paralleled and when external name severs ask a top name server for help to resolve host1.dev.example.com, the top name(.com.) sever will tell the external one to check with the name server for example.com (by returning its IP address). When the external name server brings the question to the name server for example.com, the information of dev.example.com is already there.
    pantearli, Jun 30, 2013
  8. pennino


    Nov 22, 2013
    Likes Received:

    I think the answer lies in thinking if there is a name resolution request then would the sever First look at the delegation or look at the zone that it already has... which one is preferred first?
    webris, Nov 22, 2013
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