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I am having trouble understanding the question for my network assignment. The question states:

Discover the sequence of DNS servers your local DNS server with empty cache goes through when it find the IP address of www.case.edu by performing a series of DNS queries starting with one of the root servers [a-m].root-servers.net. To choose the root DNS server, take value X = mod 13 and use Xth root server (counting from zero: a.root-server.net is #0, …, m.root-servers.net is #12) Using a series of dig commands, follow the delegation chain.

Does the assignment actually want me to query [a-m].root-servers.net, or is root-server.net a holder value for some other url that I need to find by performing a dig query on www.case.edu. I just would like help understanding the question not looking for homework answers. Thanks for any help.

Daniel Kobe
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    Why aren't you asking your instructor? How would we know what the intent of the question is as it relates to the steps it's asking you to perform? – joeqwerty Feb 10 '16 at 18:24
  • Not a particularly helpful instructor, I thought perhaps someone who knew more than I would be able to understand the question. – Daniel Kobe Feb 10 '16 at 18:37
  • OK. It's just that I don't know how we can provide an answer as to the intent of the question. It's clear to me what they're asking but it's not clear to me regarding the methodology it's suggesting. It's really just asking you to follow the recursion "chain" for a DNS query where the answer isn't already cached. – joeqwerty Feb 10 '16 at 18:39

1 Answers1

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a.root-servers.net through m.root-servers.net are indeed the actual names (not URLs, but that is probably beyond the point) of the nameservers that host the root zone (aka .).

You can confirm this list with the command dig . NS.

It sounds like the idea of the question is to do eg dig @a.root-servers.net www.case.edu +norec, get delegation information (in the authority section), repeat the process querying one of the nameservers you were referred to, etc, etc.

As for the end result, you may want to have the output of dig +trace +all www.case.edu as a reference point, even if the instructions are to do it in a more manual way.

Håkan Lindqvist
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