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Vedran Matica's avatar
Vedran Matica
Copper Contributor
Jan 29, 2018

OMS DNS Analytics solution discrepancy

I have configured custom OMS workspace with the DNS Analytics solution enabled. For testing purposes I have generated 43K+ random name resolution queries on test VM against the DNS server that is reporting to OMS. When searching collected data of the DnsEvents type, I see that only handful of queries originating from the test VM are captured on the OMS side. There is great discrepancy in what I expect to be captured and what I see in Log Analytics search results.

  • Vedran Matica's avatar
    Vedran Matica
    Jan 30, 2018

    Noa,

     

    I figured it out in the meantime. Random domain name lookup queries were generated with characters which are invalid according to the DNS RFC specification. After excluding invalid characters from lookups, I am getting results which are aligned with the testing scenario.

     

    Kind regards,

    Vedran

  • Hi,

    Possible reasons could be:

    1. Ingestion time - it usually takes around 10 minutes for events to be ingested and searchable)

    2. Client capping - the UI client caps the results at 10K. The API will return the full set of results.

    3. Query - by default, queries are not sorted by anything. When you review your query results, bare that in mind.

     

    Noa

    • Vedran Matica's avatar
      Vedran Matica
      Copper Contributor

      Noa,

       

      I ran Log Analytics searches few hours after generating random name resolution lookup queries so data should have been ingested by then.

       

      Besides that, the number of results is far from the UI limit.

       

      Vedran

      • Noa Kuperberg's avatar
        Noa Kuperberg
        Icon for Microsoft rankMicrosoft

        Hi Verdan, in that case I would contact support to review what went wrong.

        Noa

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