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Cisco 200-301: What is the Purpose of Iterative DNS Query in Domain Name Resolution?

By: Author Alex Lim

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Categories Exam

Learn about the role of iterative DNS queries in the domain name resolution process. Discover how a DNS client contacts multiple servers to find the correct information.

Table of Contents

Question

Which function does an iterative DNS query serve in the domain name resolution process?

A. Obtain information directly from all root DNS servers configured within the scope.
B. Encrypt communication automatically between DNS clients and servers.
C. Allow a DNS client to contact several DNS servers until the correct information is found.
D. Update records dynamically across multiple DNS servers at the same time.

Answer

C. Allow a DNS client to contact several DNS servers until the correct information is found.

Explanation

An iterative DNS query allows a DNS client to contact several DNS servers in sequence until it finds the server that has the information needed to resolve a domain name.

The process works like this:

  1. The client sends a query to its configured DNS server (often the ISP’s server).
  2. If that server doesn’t have the answer, it replies with a referral to another DNS server that is more likely to know, such as a root name server.
  3. The client then sends the query to the referred server.
  4. This process repeats, with the client receiving referrals and querying additional servers in turn, until a server is reached that knows the IP address for the requested domain name.
  5. That server provides the final answer back to the client.

So in summary, iterative queries allow a DNS client to “iterate” through multiple DNS servers, following a chain of referrals, until the client obtains the information it needs to resolve the domain name. This is more efficient than having the client query servers at random until it luckily finds one with the answer.

The correct answer is therefore C: Allow a DNS client to contact several DNS servers until the correct information is found.

The other options are incorrect:
A) The client does not directly query all root servers.
B) Iterative queries do not automatically encrypt DNS communication.
D) A single iterative query does not update records across multiple servers.

Cisco 200-301 certification exam assessment practice question and answer (Q&A) dump including multiple choice questions (MCQ) and objective type questions, with detail explanation and reference available free, helpful to pass the Cisco 200-301 exam and earn Cisco 200-301 certification.