question about how a particular dig works ...

[M. Meadows]

Thanks Kevin. I understand how the chained alias works. Sorry, I didn't explain my question very well.

I can see that the 8.8.8.8 google public dns server gets an answer.

I know that this domain has a cname coexisting with an SOA record and NS records ... both of which I have read are a bad thing. And I've seen the other reply that indicates that this combination of records in a zone file wouldn't even load in BIND ... so it's done with some other more forgiving DNS app. 

What I also see (but failed to explain) is that we have a local nameserver that can't find an answer to the dig www.careerone.com.au query. Gets no record back. Our local nameserver is an AD server that just throws up its imaginary hands in despair. So is this what we should expect from this problematic DNS setup in the www.careerone.com.au zone file? Erratic or somewhat erratic results? Just curious why google and some other public facing dns servers get an answer when our own local nameserver can't figure it out.



Date: Tue, 18 Sep 2012 11:18:58 -0400
From: kcd at chrysler.com
To: bind-users at lists.isc.org
Subject: Re: question about how a particular dig works ...


  
    
  
  
    On 9/18/2012 9:45 AM, M. Meadows wrote:

    
    
      
      
        

        dig www.careerone.com.au +short @8.8.8.8

        www.careerone.com.au.edgesuite.net.

        a903.g.akamai.net.

        208.44.23.99

        208.44.23.121

        

        Why does the above dig work when 

        

        dig careerone.com.au +nssearch @8.8.8.8

        SOA dns0.news.com.au. hostmaster.news.com.au. 2012082200 3600
        1200 86400 1200 from server usw1.akam.net in 106 ms.

        SOA dns0.news.com.au. hostmaster.news.com.au. 2012082200 3600
        1200 86400 1200 from server usw4.akam.net in 136 ms.

        SOA dns0.news.com.au. hostmaster.news.com.au. 2012082200 3600
        1200 86400 1200 from server usc4.akam.net in 124 ms.

        SOA dns0.news.com.au. hostmaster.news.com.au. 2012082200 3600
        1200 86400 1200 from server usc1.akam.net in 40 ms.

        SOA dns0.news.com.au. hostmaster.news.com.au. 2012082200 3600
        1200 86400 1200 from server usw5.akam.net in 190 ms.

        SOA dns0.news.com.au. hostmaster.news.com.au. 2012082200 3600
        1200 86400 1200 from server ns1-24.akam.net in 171 ms.

        SOA dns0.news.com.au. hostmaster.news.com.au. 2012082200 3600
        1200 86400 1200 from server asia1.akam.net in 161 ms.

        SOA dns0.news.com.au. hostmaster.news.com.au. 2012082200 3600
        1200 86400 1200 from server ns1-50.akam.net in 161 ms.

        

        shows 8 auth nameservers for careerone.com.au

        

        and if you use 

        

        dig www.careerone.com.au +short @<any of the 8 auth
        nameservers> 

        

        you get no answer.

        

        How does that work? Where does the 8.8.8.8 google public dns
        server get its answer from?

        

      
    
    www.careerone.com.au is an alias (through chained aliasing)
    ultimately to a903.g.akamai.net. To get an authoritative answer for
    a903g.akamai.net you'd need to ask one of the g.akamai.net
    nameservers. Which is presumably what Google's public resolver did
    to get the answers it returned to your query.

    

                                                                       
                                                                       
                - Kevin

  


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