DNS Issue, Cannot resolve Web Site

[thesham]

Hi All,

Im having an issue in that i have to DC's and both running DNS.

I have a problem that i cannot resolve a specific web address, if i type in the IP address it works with no problem, until i hit a link within the site and again it cannot resolve the url.

If i do a Nslookup it will not work either, nslookup *******.com this is the results


c:\nslookup *******.com

Server: server.mydomain.com
Address 192.168.x.x

Name: *******.com
(It will not resolve to the IP address, leaving it blank)




I have tried this on all servers and the output is the same, however sometimes the website does get resolved and then other times it will not.

This is leaving me very confused.


Windows 2003 Server (SP2) DNS1
Windows 2000 (SP4) DNS2

Any suggestions would be much appreciated

Cheers,

 

[Ztrek7]

Are you using forwarders or root hints?

 

[thesham]

We are using Forwarders

Hope this helps

 

[Ztrek7]

If you forward to your ISP's DNS, then I would nslookup on that box and see if it resolves.

Also, try using root hints and see what happens.

 

[gb0mb]

If this is for only one specific site is it possible that it is their name servers having issues?

When a query is done if they host their own dns the eventual resolution is done on their Name Servers.

Gb0mb

........99.9% User Error........

 

[BenyG]

I have a similar issue - the nameservers for a particular domain are down and as I do not normally use forwarders and there is no cached lookup the resolve is not working.

My ISPs DNS resolves it fine so I thought turning on forwarders would fix it - but it hasnt. The ISP DNS comes back with the result in over 30 seconds so it times out. -When my own DNS does a lookup on my ISPs DNS due to a forwarder it takes longer (and is thus hitting the timeout) than it does when it is done directly.

Why would my ISP DNS take longer to respond to a query when it is actioned as a forwarder than when run directly though nslookup?

Thanks for any help,



Benjamin

 

[wchull]

Here are a couple of things to try and/or think about.

First off you mentioned the fact that if you use a URL with the IP address it can't find the page when specify a site (i.e.

http://192.168.xxx.xxx/site).

It is important to note that anything behind the IP address or the domain name (i.e. server.mydomain.com)is handled as a redirection by the server itself. The server is probably looking for a url like

http://server.mydomain.com/site.

When the "server" sees this URL string it knows to take you to the site page however it can't recognize the same string when using the IP address as the strings are different.

Getting back to your problem Is the site you are trying to reach your site our someone elses site? If it is someone elses site then I would go to

http://www.dnsstuff.com

and scroll down the page to the test called DNS Lookup and when there try out the dns name you're trying to reach (i.e. server.mydomain.com). This test will tell you what the "authoritative answer" to the query is and where it came from. Getting an "authoritative" answer will confirm that the other party has that server in their public DNS. If the authoritative answer is what you expected it to be then look inside DNS and see who you are forwarding to and try an NSLookup using the server subcommand to set NSLookup to use your ISP's server instead of your own. Note that your ISP should come back with a non-authoritative answer which is OK providing that they are the same. If different then your ISP or some other server up the chain as a bad cache. If the authoritative and non-authoritative answers are then same then your problem is probably internal and you should then run the nslookup command using some of the debug features. For more info on NSLookup's suite of commands first type nslookup at a command prompt and then at the carat type help.

 

[BenyG]

The site always works fine when the IP address is given - it is just that the responce from my ISP DNS when queried as a forwarder is 30+ seconds but when I do it myself through nslookup it comes back straight away.

That said, on investigating it further there are some issues at the site's end but I wasjust wondering why a DNS responce would be slower when queried through a forwarder.

Benjamin

 

[gb0mb]

First thought is that the forwarder has some delay set or maybe retries multiple times. I am curious for the correct answer myself.

Gb0mb

........99.9% User Error........

 

[lhuegele]

Try removing forwarders and using root hints instead.

Good luck,

 

[r8j8t]

BenyG
If you use forwarders in order to speed up the repsonse time you need to disable recursion for the particular domain on which you ae using forwarder.
If recursion is not diabled which is deafult your server tries to reolve the querry localy once it does not get response from your forwarder.
But note if you disable recursion then you will be fully dependent on forwrder for your name resolution and will not be able to use local cache or root hints as alternative.