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I've got 2 machines on the same sub-net running Debian 5.0. They use the same DNS (/etc/resolv.conf), they route to the same gateway (#route) and they have the same iptables settings (#iptables -L). I can ping from both of them, both to IP addresses and to host names. I can run #host and get the same results on both of them. But the problem is that on one of them, I can't wget or curl.

So on machine 1 everything is OK, but on machine 2 (with the same settings as machine 1) I can't wget or curl.

The error I get is:

# wget
--2009-10-20 16:38:36--
Resolving failed: Name or service not known.
wget: unable to resolve host address `'

But on machine 1 it has no problem to wget or curl and returns:

# wget
--2009-10-20 16:43:55--
Connecting to||:80... connected.
HTTP request sent, awaiting response... 301 Moved Permanently
Saving to: `index.html.3'


I'm hoping someone here can point me in the right direction here so that I can possibly fix this issue :)

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migrated from Oct 20 '09 at 16:44

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This is most probably not related to wget but to a networking issue. – jldupont Oct 20 '09 at 16:43
do you have a proxy setting in the environment .. my work machine did :-( – lexu Oct 20 '09 at 16:44
Try "host", not "host", on server 2. – Bill Weiss Oct 20 '09 at 17:43

7 Answers 7

Check your /etc/nsswitch.conf file (or whatever the equivalent is on Debian if it's not that).

host and nslookup always do DNS lookups.

However other applications will look in NSS first for other naming systems (e.g. /etc/hosts, NIS, etc). If something else is configured but not working it could prevent the application from ever trying the DNS.

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The canonical way to check the resolver is running getent hosts This uses nsswitch.conf and then resolv.conf as required. – Joe Nov 5 '09 at 19:08

Thanks for the answers you guys!

It was the nsswitch.conf file. I had setup LDAP from a tutorial that told me to use this line in hosts:

hosts: files mdns4_minimal [NOTFOUND=return] dns mdns4

When I changed it to this:

hosts: files dns mdns4_minimal [NOTFOUND=return] mdns4

It works without a problem. So I guess the nsswitch config file was making it return null if not found in files or mdns4_minimal, right?

Thanks for your help!

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You should probably accept Alnitak's answer. – Dan Carley Oct 21 '09 at 13:23
Yeah, how do I do that? :-/ – Maggi Trymbill Oct 26 '09 at 21:08
Accept by clicking the "V" next to the vote score. :) – Redsandro Mar 31 '13 at 21:36



so that we see what DNS servers you are using on both boxes.

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Could there be an invalid proxy configured on the machine with the error? Try this:

# wget --no-proxy
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The first thing to try is checking whether DNS works correctly.

# host has address has address has address

If you don't get that response, check /etc/resolv.conf and find the name servers listed in that file. Can you ping each of them?

Try querying each of them individually:

# host

Can you resolve another host?

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I had the same problem, but next to changing /etc/nsswitch.conf:

hosts: files dns mdns4_minimal [NOTFOUND=return] mdns4

I also had to change the name servers:

Change /etc/resolv.conf so it points to the google nameservers. The ones added by network manager don't work for me.

# RED 2013-03-31
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Thanks, anonymous, for the constructive comment on the downvote. – Redsandro Sep 23 '14 at 11:21

I think you cannot change /etc/resolv.conf directly.

You need to create an /etc/resolv.conf.head file to do it.

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