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why stub zone

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  • why stub zone

    Can any one tell me about the benefits of stub zone.

    As far as I know about stub zone :-

    1)it contains only A,SOA and NS record.
    2)uses TCP packets, instead of UDP.
    3) supports AD integration.
    4)no need for zone transfer

    Above features are not available in Secondary DNS servers.

    But limitations of stub zone (if I know) are the same:

    1)we cannot add/modify/delete any records
    2)dependent on primary DNS
    3)If we create a stub zone in a remote location which is connected with Primary DNS server over a slow link,. then all queries will be send from stub to primary DNS.

    Then in what scenario shall we use Stub zone ?

  • #2
    Re: why stub zone

    Understanding stub zones

    A stub zone is a copy of a zone that contains only those resource records necessary to identify the authoritative Domain Name System (DNS) servers for that zone. A stub zone is used to resolve names between separate DNS namespaces. This type of resolution may be necessary when a corporate merger requires that the DNS servers for two separate DNS namespaces resolve names for clients in both namespaces.

    as taken from

    full article gives a good explanation of why you would want to use one.


    • #3
      Re: why stub zone

      As far as i see, it occupies less space compared to delegated zone or secondary zone.

      Conditional forwarding and stub zones does the same task. Conditional forwarding is static and stub zone is dynamic. Any change in primary zone of stub will be updated to stub which is not the case in conditional forwarding.

      Stub zone is useful where the administration is not required/ less occupancy of DNS space/ Business requirements


      • #4
        Re: why stub zone

        Then I think everybody will prefer to use Secondary zone ...because if remote location is having one Secondary DNS..then there is no need to have the link up all the time... In case of stub zone, there must be connectivity between primary and stub zone. In case of secondary zone, no need for permanent connectivity with primary zone. Secondary zone already contains all the RRs, it can resolve DNS queries at its own.. no need to forward it to Primary DNS.

        Is it correct ?


        • #5
          Re: why stub zone

          U're right, but secondary zones gets updated from primary zone every 15 minutes (default)
          Also A Zone transfer will occur during any of the following scenarios:
          -When starting the DNS Service on the secondary DNS server.
          -When the refresh time expires.
          -When changes are saved to the Primary Zone file and there is a Notify List.

          If you still want to override the refresh time, change the refresh time in SOA record of primary zone. (refer -


          • #6
            Re: why stub zone

            Stub Zone will be only used in the active directory infrastruture.
            But secondary zone will be used in both stand alone without AD and also with AD.



            • #7
              Re: why stub zone

              Stub zone resolution
              When a DNS client performs a recursive query operation on a DNS server hosting a stub zone, the DNS server uses the resource records in the stub zone to resolve the query. The DNS server sends an iterative query to the authoritative DNS servers specified in the NS resource records of the stub zone as if it were using NS resource records in its cache. If the DNS server cannot find the authoritative DNS servers in its stub zone, the DNS server hosting the stub zone attempts standard recursion using its root hints.
              The DNS server will store the resource records it receives from the authoritative DNS servers listed in a stub zone in its cache, but it will not store these resource records in the stub zone itself; only the SOA, NS, and glue A resource records returned in response to the query are stored in the stub zone. The resource records stored in the cache are cached according to the Time-to-Live (TTL) value in each resource record. The SOA, NS, and glue A resource records, which are not written to cache, expire according to the expire interval specified in the stub zone's SOA record, which is created during the creation of the stub zone and updated during transfers to the stub zone from the original, primary zone.
              If the query was an iterative query, the DNS server returns a referral containing the servers specified in the stub zone.
              Last edited by Wired; 24th August 2010, 15:34. Reason: cited source


              • #8
                Re: why stub zone

                Thanks Everyone for sharing your experience with me on Stub Zone.