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In a specific setup (Specific Website) DNS server is getting request for specific record (www.example.com) thus it's confident that the request will be followed by series of others (x.example.com, y.example.com, z.example.com).

Is it possible to gain reduction in these other requests if their RRs are included in additional section of DNS response (preemptive responding)? I.e.

DNS QUERY
  www A

ANSWERS
  www A IN 11.22.33.44

AUTHORITATIVE NAMESERVERS
  NS IN ns1
  NS IN ns2

ADDITIONAL RECORDS
  x   A IN 55.66.77.88
  y   A IN 99.11.22.33
  z   A IN 44.55.66.77

The intention is to use such pre-populated responses:

  1. to speed up overall interaction with domain DNS server is serving (primary objective).
  2. to reduce DNS server load (secondary objective).

Is there any DNS service provider that is expert in this type of optimizations? Or let me know about argumented write-up on the topic and why the above is not possible.

share|improve this question
    
Can you be specific about your specific setup and specific record? It's pretty hard to help if you're not specific. –  voretaq7 Aug 30 '11 at 1:15
1  
Seconding @voretaq7's comment about details. Usually in DNS land the round trip time itself and the TTL are the biggest things(read: several orders of magnitude) you can use to improve performance. You don't mention why those won't help or what you've already done there. –  polynomial Aug 30 '11 at 1:23
    
This is explicitly tying the DNS protocol to HTTP-only? –  Steve-o Aug 30 '11 at 4:54
    
Sorry I do not know what HTTP-only DNS protocol is ;) And yes, the question above is about DNS working to help HTTP client have less questions to DNS, preferably single request and sigle response containing all information HTTP client will need in future. –  myroslav Aug 30 '11 at 7:26
    
I've updated question with specific details. –  myroslav Aug 31 '11 at 10:11
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1 Answer

It can never be confident of others. For example:

website http://www.test.com/index.html (test.com is lookup one, then www.test.com is #2) has 20 images, all hosted on different sites.

DNS can not predict this without loading the HTML first, but thats what the client is for. The client's browser will decode the HTML and request all the sources to the images, usually all at once.

What if the page changes and they update all the links of images?

BL: It's never going to be able to PREDICT dns requests, but it CAN cache prevoius requests.

The TTL of the record (expiration time) will let the DNS server when to purge that record from the cache.

That's just about it.

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Controlling the test.com and index.html is the key. The question is not about PREDICTION, but about KNOWLEDGE, what requests follow the initial one. If one knows what is request pattern, can one pack as many responses in initial answer? –  myroslav Aug 30 '11 at 6:55
    
I've updated question with specific details. DNS server is not expected to be "intellectual". I just want to inject x, y, and z records whenever there is request for www record. –  myroslav Aug 31 '11 at 10:13
    
I don't think this is possible without custom dns software. I mean, if it was, everybody would be doing this. Sorry. –  U4iK_HaZe Aug 31 '11 at 10:39
    
Is this just round robin? –  U4iK_HaZe Aug 31 '11 at 10:44
    
The x, y, and z RRs are different names and different IPs. They represent addresses of subdomains hosting resources for the webpages hosted on primary www sobdomain. I understand that it is very custom, and requesting to point me into direction of DNS provider that does that or does not, and explains why it is not possible. –  myroslav Aug 31 '11 at 12:13
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