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How to resolve selected internal domain name to an external DNS

Posted on 2009-07-16
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Last Modified: 2013-12-25
We have an outside vendor hosting our website www.YYY.com.
Our internal network has the same network name YYY.com.

We setup an A record in our internal DNS server to resolve www.YYY.com to the outside IP address.

The problem is that the vendor hosting our site changes the IP address frequently and we would have to keep on changing our internal A record to resolve the correct IP address. We are tied with a contract to the hosting site (inherent issue).

How can we selectively resolve just the www.YYY.com to the external DNS server so the correct IP address is resolved correctly everytime the hosting company changes the IP address without needing manual intervention?

Our internal DNS server is a Windows 2003 Server that has DNS forwarding enabled.

Thank You.
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Question by:hkit0630
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by:sorrillo
sorrillo earned 250 total points
ID: 24872357
You need to know which DNS servers resolve www.YYY.com. You can use nslookup to get this information.

Those should be the hosting DNS servers.

Then in your dns server you need to create a delegated zone for www.YYY.com and assign the hosting dns servers as the dns server where this zone is delegated.

This should do the work.
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by:andrewc2189
ID: 24872422
Out of curiosity, where do internal clients resolve www.YYY.com to without the A record? Do requests not get forwarded to the external DNS server without the A record? As you said, the inherent issue is that it's not a static IP. I have heard of people with setups that somehow update their records to reflect changes in dynamic addresses using home servers, I'll try to find more info on that.
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by:andrewc2189
ID: 24872480
sorrillo makes more sense to me on this one, I would say to take that route over the ways people run websites out of their home! Cheers.
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by:acronyms
ID: 24872730
Is that the only domain name that goes to your Website??

If you had another DNS name that pointed to your website i.e. www.YYY.co.uk then you could set the alias up for www to point to that.

You have been tripped up by using the external domain name as you internal rather that yyy.local.

Regards

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Author Comment

by:hkit0630
ID: 24873060
Thank you for your replies.

Sorillo -
  • deleted the A record (www) in my zone YYY.com
  • created a new zone - www.YYY.com and setup the appropriate Name server that is resolving this url.
  • flushed the DNS cache for all the internal DNS servers
  • nslookup for www.YYY.com results to only the www.YYY.com and no ip address
  • ping www.YYY.com only gives me an error that cannot find host www.YYY.com
What am i missing here??
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by:sorrillo
ID: 24873436
nslookup for www.YYY.com results to only the www.YYY.com and no ip address

I don't understand what you mean. Could you post the nslookup result ? (masking domain name if you want).

You should also flush the local dns cache using ipconfig /flushdns before the ping test.
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Author Comment

by:hkit0630
ID: 24873713
i flushed the dns cache on the DNS servers and local PC that i'm using.

i attached a screen shot of the nslookup that shows no IP address resolved and ping result
nslookup.JPG
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Expert Comment

by:sohil
ID: 24873809
Sorillo:

I had a similar situation sometime ago when my hosting company's DNS servers were unreliable for a period of 3 months.

I forwarded my queries to XO Communicaionns and Cogent DNS servers. Also, I set my DNS cache for quick expiration. It did overwork my DNS servers, but worked like a charm for the short period that I needed it to work.
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Author Comment

by:hkit0630
ID: 24874426
Sohil:

I change the DNS cache expiration but still not getting any resolution for the www.YYY.com
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Expert Comment

by:acronyms
ID: 24876652
You never will get this to resolve as you are asking because your internal domain name is the same as your external name. The only way to do it is point the alias of www to a different external domain name so your internal users can view the webpage.

If your IP was static then you could put this in DNS but as you have stated your ISP keeps changing this so it wont last long. You want to eliminate the need for you to change the IP address.

I don't believe you can achieve this using internal methods to resolution your are seeking.
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by:allen-davis
ID: 24885005
I think andrewc2189 already asked this but maybe in a different way:

If you remove www.yyy.com from your DNS completely, what happens? I think the DNS by default should look up the external IP address from "the Internet at large" once it does not find it locally.  The yyy.com address you have setup should still resolve to the internal address but the www.yyy.com should resolve to the external address I believe unless you run into issues with yyy.com interfering with your ability to resolve www.yyy.com externally.
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by:acronyms
acronyms earned 250 total points
ID: 24892982
Why would a DNS Server go external if it believes it is the root of that domain? It wouldn't!!

DNS procedure as I believe it happens:

1. User in xxx.local needs to resolve the web address www.yyy.com.
2. His local server is server1.xxx.local and the users request has been checked against the local database with no joy.
3. server1.xxx.local then contacts the external DNS and says where is the root of .com. which it is given a response.
4. That response is used and the root of yyy.com is then contacted and asked where www should be resolved to. This then gives the IP address to the server and then to the client hence you get the DNS CACHE on the server if you look at Windows DNS MMC.

In this scenario.

1. User is in yyy.com and wants www.yyy.com.
2. His local server is server1.yyy.com and the local database is check and a response is given to the old web server that was manually put in there which is wrong now due to the ISP. Error 404 displayed.

OR

His local server checks the DNS database and says " Sorry no entry in here for www" error 404 displayed for the user. There would be no forward as it is the root of yyy.com

Hope this makes sense.

 
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hkit0630 earned 0 total points
ID: 24919603
any other options?
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Author Comment

by:hkit0630
ID: 24930560
no viable solution
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by:acronyms
ID: 24935065
Scrap your internal domain and set it up correctly. Lots of work though dependent on your architecture.



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Author Comment

by:hkit0630
ID: 24937406
i almost died laughing..

thanks for making my friday !!!
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by:sorrillo
ID: 24940193
I might be able to explain why my solution did not work on your case. I must admit I never used myself, it was just theoretical.

Anyways, I tested some domains to see what happened.

Using experts-exchange.com as a testing domain did not work as expected. I believe this is what went wrong:
www.experts-exchange.com      canonical name = experts-exchange.com

www.experts-exchange.com points to the domain itself which will not have the correct resolution as it can not be delegated.

Using sun.com as a testing domain did work as expected. That's why:
Name:    www.sun.com
Address: 72.5.124.61

www.sun.com does not point anywhere else, it just returns the IP.

Your case might be like www.experts-exchange.com, you can confirm it with nslookup ans see if it just resolves to an ip or to the domain without the www.

Anyways, this solution did not solve your problem so this comment is not an objection, just a clarification.

Greetings.
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