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DNS concepts RRS feed

  • Question

  • Hi Guys,

    I am studying DNS these days. I am very confuse on 2 questions that arises in my mind.

    Question1- During recursion, When a DNS server A query another DNS server B. What will B do, if that server doesn't found the answer to that query. Will it query the DNS servers in its forwarder list or simply return no result found to A.

    Question2 - On what basis, a DNS server provide referral servers for querying to another DNS server. 

    Wednesday, December 13, 2017 1:14 PM

Answers

  • Hi,

    Recursion is a DNS Server function in which a series of several iterative queries are issued by one DNS Server to other DNS servers, when responding to a Recursive Query issued by a DNS client. 
    The queried DNS servers return referrals which the querying server follows until it gets a definitive answer. Recursion always ends with a server that owns the namespace either giving a positive or negative reply. 
    Recursion enables the server to “go to work” on behalf of the client to resolve a query. The DNS Server performing recursion “does the work” of querying multiple other DNS servers until it has a suitable answer for the client. This takes the burden of name resolution off of the client, and places it on the local DNS Server.
    Referral
    This is a possible answer to an iterative query. If the queried server doesn’t have a positive or negative answer to return, it refers the querying server to the closest known DNS server that matches the name being queried.

    More information about DNS ,you could refer to it :

    https://technet.microsoft.com/en-us/library/dd197552(v=ws.10).aspx

    Best Regards,
    Frank


    Please remember to mark the replies as answers if they help and unmark them if they provide no help.
    If you have feedback for TechNet Subscriber Support, contact tnmff@microsoft.com.


    Wednesday, December 27, 2017 2:43 AM

All replies


  • Hi,

    >>Will it query the DNS servers in its forwarder list or simply return no result found to A.

    Yes, it would do .

    >>On what basis, a DNS server provide referral servers for querying to another DNS server. 

     If there is no positive or negative answer to  server querying,a DNS server provide referral which  contains a list of alternate servers for querying to another DNS server. 

    Best Regards,
    Frank


    Please remember to mark the replies as answers if they help and unmark them if they provide no help.
    If you have feedback for TechNet Subscriber Support, contact tnmff@microsoft.com.

    Thursday, December 14, 2017 10:37 AM

  • Hi,
    Just checking in to see if the information provided was helpful. Please let us know if you would like further assistance.

    Best Regards,

    Frank

    Please remember to mark the replies as answers if they help and unmark them if they provide no help.
    If you have feedback for TechNet Subscriber Support, contact tnmff@microsoft.com.

    Monday, December 18, 2017 8:55 AM
  • Hi,

    Was your issue resolved? 

    If you resolved it using our solution, please "mark it as answer" to help other community members find the helpful reply quickly.
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    If no, please reply and tell us the current situation in order to provide further help.

    Best Regards,
    Frank

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    If you have feedback for TechNet Subscriber Support, contact tnmff@microsoft.com.

    Wednesday, December 20, 2017 8:13 AM
  • Sorry for late revert, I was working on something else.

    Both the answers you provided is little bit contradictory. If B DNS server query other servers in its forward list and still not able to find the query result, than what referral it will provide to A.

    Tuesday, December 26, 2017 9:50 AM
  • Hi,

    Recursion is a DNS Server function in which a series of several iterative queries are issued by one DNS Server to other DNS servers, when responding to a Recursive Query issued by a DNS client. 
    The queried DNS servers return referrals which the querying server follows until it gets a definitive answer. Recursion always ends with a server that owns the namespace either giving a positive or negative reply. 
    Recursion enables the server to “go to work” on behalf of the client to resolve a query. The DNS Server performing recursion “does the work” of querying multiple other DNS servers until it has a suitable answer for the client. This takes the burden of name resolution off of the client, and places it on the local DNS Server.
    Referral
    This is a possible answer to an iterative query. If the queried server doesn’t have a positive or negative answer to return, it refers the querying server to the closest known DNS server that matches the name being queried.

    More information about DNS ,you could refer to it :

    https://technet.microsoft.com/en-us/library/dd197552(v=ws.10).aspx

    Best Regards,
    Frank


    Please remember to mark the replies as answers if they help and unmark them if they provide no help.
    If you have feedback for TechNet Subscriber Support, contact tnmff@microsoft.com.


    Wednesday, December 27, 2017 2:43 AM
  • Thanks...
    Thursday, December 28, 2017 3:29 AM