Solved

DNS forwarder question

Posted on 2008-06-25
4
253 Views
Last Modified: 2010-04-07
If you configure a DNS server to use a forwarder, would a wireshark capture show DNS traffic between just you and the forwarder or does the forwarder return the IP of  the authoritative DNS server and would your DNS server go there to finally resolve the name to IP?

I'm trying to figure out if my forwarder is working correctly.


0
Comment
Question by:jjc_mn
  • 2
4 Comments
 
LVL 14

Expert Comment

by:cuziyq
Comment Utility
Your DNS server would forward the request and the request would be sent back to your DNS server.  The client making the request would be unaware that the request had been forwarded.
0
 
LVL 19

Expert Comment

by:feptias
Comment Utility
You are describing the difference between iterative and recursive DNS. On the Windows DNS server, on the "Forwarders" tab, there is tick box option "Do not use recursion for this domain". When the option is ticked, it means you want your DNS server to only query the forwarder (i.e. your DNS server should not go elsewhere to finally resolve the name).
0
 

Author Comment

by:jjc_mn
Comment Utility
Actually I'm on Lunix not Windows but that should  not matter.

Also I'm disregarding traffic between my DNS server and the client that makes the request. I'm only looking at server to server traffic.

You said :  "your DNS server should not go elsewhere to finally resolve the name". From my wireshark trace it looks like it asks the forwarder and the forwarder comes back and gives it the DNS SOA and then my server goes to the SOA to resolve.

So that behavior is not correct?
0
 
LVL 19

Accepted Solution

by:
feptias earned 500 total points
Comment Utility
You are possibly mis-interpreting what I meant to say!
In effect, what I said was: "When that option is ticked your DNS server should not go elsewhere..."

When the option is *not* ticked, then your DNS server is very likely to start interrogating other DNS servers. That process is called recursion. I have never investigated the process down to the level of running a packet trace, but SOA records contain information about the primary DNS server for the domain so it makes some sense.

I don't know what the equivalent is of that tick box option in Linux, but no doubt there is an equivalent in the config settings. I believe it is called "slaving" when one DNS server devolves all responsibility for name resolution to the forwarder.
0

Featured Post

What Security Threats Are You Missing?

Enhance your security with threat intelligence from the web. Get trending threat insights on hackers, exploits, and suspicious IP addresses delivered to your inbox with our free Cyber Daily.

Join & Write a Comment

One of the most often confused topics in the area DNS is the idea of GLUE records. Specifically, what they are, when they are needed, when they are provided, and how they are created. First, WHAT IS GLUE? To understand GLUE, you must first under…
Resolve DNS query failed errors for Exchange
It is a freely distributed piece of software for such tasks as photo retouching, image composition and image authoring. It works on many operating systems, in many languages.
This video explains how to create simple products associated to Magento configurable product and offers fast way of their generation with Store Manager for Magento tool.

744 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question

Need Help in Real-Time?

Connect with top rated Experts

11 Experts available now in Live!

Get 1:1 Help Now