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I'm running centos 5.8 on a local machine at home. Today I was trying to analyze the DNS-Lookup via dig.

$ dig +trace -t A www.heise.de.

This is giving me something like this as a response

de.         172800  IN  NS  f.nic.de.
de.         172800  IN  NS  z.nic.de.
de.         172800  IN  NS  s.de.net.
de.         172800  IN  NS  n.de.net.
de.         172800  IN  NS  a.nic.de.
de.         172800  IN  NS  l.de.net.
;; Received 344 bytes from 192.58.128.30#53(192.58.128.30) in 49 ms

In contrast my dedicated CentOS machine is returning the following

 de.            172800  IN  NS  a.nic.de.
 de.            172800  IN  NS  n.de.net.
 de.            172800  IN  NS  f.nic.de.
 de.            172800  IN  NS  z.nic.de.
 de.            172800  IN  NS  l.de.net.
 de.            172800  IN  NS  s.de.net.
 ;; Received 344 bytes from 192.58.128.30#53(j.root-servers.net) in 32 ms

As you can see, the last line is different. Any idea why my dedicated machine is giving me the host name of the responding DNS-Server and my local machine is only returning the ip-address?

Thanks in advance

UPDATE

The reverse DNS-Lookup is working without any problems. Also, I just checked this on my local mac and...exactly the same problem occurs. Is it possible that this has to do with the local router/modem/ISP?

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  • Maybe it's simply a dig -v issue ?
    – Sandman4
    Nov 3, 2012 at 21:40

2 Answers 2

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If the reverse lookup fails on one machine but succeeds on the other, then the problem is probably just a difference in the machines' resolv.conf. Perhaps you have a 'search' or 'domain' field specified in the second machine's resolv.conf, or perhaps you are using different nameservers all together. What is your DNS setup like? You said you're at home; does this mean you are just using external DNS like google or your ISP, or do you have your own local DNS?

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  • The reverse lookup is working on my local box. I'm using the ISP default DNS.
    – travisbotello
    Nov 1, 2012 at 21:16
  • Very very strange. I just checked this on my mac and...exactly the same problem occurs. Is it possible that this has to do with the local router/modem/ISP?
    – travisbotello
    Nov 1, 2012 at 21:45
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The difference between them is nothing more than a reverse-lookup on the IP address that returned the response.

Can you do the reverse lookup yourself from your local box?

dig -x 192.58.128.30

If this fails, that's the reason.

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  • The reverse lookup from my local box is working. Any other ideas?
    – travisbotello
    Nov 1, 2012 at 21:12

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