View Full Version : Browser problem: Cannot find server

17th October 2012, 05:05 PM
I am writing the URL

into the browser.

But FF or another browser very often does not open the URL

Cannot find server.

What can I do?

I repeat
with reload
and maybe then or wait 10 minutes
I can reach the url.

This happen with all urls not only with the forum here.

How can I improve the browser.

It is not a problem of FF, now I am using FF
all other browsers have this problem.

Thank You for help.

17th October 2012, 05:36 PM
If it's happening with all urls and all browsers it could be a connection problem. Have you checked the router?

17th October 2012, 06:34 PM
It could also be a DNS issue you might try an alternate server such as Google, or OpenDNS, open the network manager and edit your connection and place these numbers into the box that says DNS servers seperated by comma and then try the browser. Alot of ISP's have crummy DNS servers.

17th October 2012, 06:35 PM
It also could be a DNS problem.

Some others have suggested directing Firefox to not try using IPv6...

17th October 2012, 06:59 PM
I just had this issue last night and for me it was the ipv6 issue. Once I turned it off I have had no problems.

I got the commands from this site: Disabling IPv6 on Fedora 17 Linux (http://www.fclose.com/b/linux/3687/disabling-ipv6-on-fedora-17-linux/)

Basically what it says is to add these 2 lines to /etc/sysctl.conf


I did this and the web was working for me just like it should.

So far I have found Fedora and openSUSE initially using IPv6 and needing to turn them off, while Ubuntu has it disabled by default or somehow makes it work.

When I went to Facebook, before adding these lines I could get into Facebook, but not see pictures that other people have posted. After adding these lines Facebook came up fine and nobody else gave me any trouble. Even doing a yum update produced no errors.

18th October 2012, 08:01 PM
You don't have to disable it on the entire system, but can disable it just for Firefox:

use the URL "about:config"

Scroll down to "network.dns.disableIPv6",

Select this and hit enter.

This eliminates the DNS timeout (about 10 minutes) when there is no IPv6 name server.

This is preferable to disabling IPv6 everywhere, as you might/will need IPv6 soon as the IPv4 addresses have run out. When the various ISPs use up what they have hoarded, they will be forced to switch to IPv6.

25th October 2012, 04:59 PM
"If it's happening with all urls and all browsers it could be a connection problem. Have you checked the router?"

Thank You for help.

What is a DNS Problem?
I was trying 10 live CDs Linux
also installed same problem.

All browsers do that.
I am sure, the router is ok.
DSL check is ok also
Upload big files and download ist ok.

New url


no contact
then repeat 10 times and then I can see the homepage.

25th October 2012, 09:44 PM
What is DNS? Well, a quick look at Wikipedia shows this: http://en.wikipedia.org/wiki/Domain_Name_System

For a less technical explanation, I like to say that it's the Internet's equivalent of Directory Assistance. It changes human-readable machine names (e.g., forums.fedoraform.org) into the actual IP address that your computer works with. I'm limiting my response to this because until you understand what DNS is the above answers probably won't make much sense, and once you do, what's above may well be all you need. Good luck and don't hesitate to ask more if needed.

1st November 2012, 08:00 PM
Good evening. Thank You for explanation DNS.
But what do I do wrong, so that the browsers have so much problems, always to find a url?

1st November 2012, 08:16 PM
I'm fairly sure that the Live CDs all get their DNS numbers from your router along with their IP address by DHCP. Do you know what DNS numbers your router is giving?

2nd November 2012, 09:00 AM
alternate server such as Google,

You have it backwards. It's either or ;-) domain name pointer google-public-dns-a.google.com. domain name pointer google-public-dns-b.google.com.

13th November 2012, 03:46 PM
Good afternoon. Also there problems claws and www. Also all Mailprogrammes doiing POP SMTP habe 20% mistake rate.
This does mean
pop no connection.
I close claws and try again
then it is working.
10 time sending 8 times it is working.

So Linux has a bad connection to the router.
Is this right?

13th November 2012, 04:36 PM
Possibly. Traceroute will give you an idea where the issue is:

traceroute servername

will show you every server a ping goes through from here to the server. If all you get is * for most of your replies, try this (as root):

traceroute -I servername

because that sends ICMP ECHO requests, that few servers ignore but requires root permissions to send. If it seems to get almost there, then fails, that just means that the final server is dropping them to avoid
DOS attacks. If the results aren't clear, post them here and I'll take a look at them.

21st November 2012, 05:57 PM
traceroute -I servername

Good afternoon.

Should I write

traceroute -I www.fedoraforum.org
or should I write

traceroute -I servername

Sorry for maybe stupid question:
What is the meaning of servername?

There are tests
testing DSL Speed
the speed is ok.

But when I said
PING check
the test is not working does mean: no result.

Thank You for help.

21st November 2012, 08:08 PM
Servername is a placeholder for whatever box you're trying to reach. Replace it as needed.

22nd November 2012, 12:29 PM
# traceroute -I www.fedoraforum.org
traceroute to www.fedoraforum.org (, 30 hops max, 60 byte packets
1 ( 1.659 ms 2.039 ms *
2 * * *
3 * * *
4 * * *
5 * * *
6 * * *
7 * * *
8 * * *
9 * * *
10 * * *
11 * * *
12 * * *
13 * * *
14 * * *
15 * * *
16 * * *
17 * * *
18 * * *
19 * * *
20 * * *
21 * * *
22 * * *
23 * * *
24 * * *
25 * * *
26 * * *
27 * * *
28 * * *
29 * * *
30 * * *

I did not understand
but I did it.

Did I do it right?

Regards and Thank You for helpl.

22nd November 2012, 06:22 PM
Yes. This is saying that the pings got to your router OK, but that no other server responded. As far as I can tell, either your router never even sent the packets out, or the server at the other end (run by your ISP) was dropping them. Talk to your ISP.

22nd November 2012, 09:41 PM
there is one other possibility, though unlikely.

The router has NAT capabilities turned off.

I don't think this is likely or you wouldn't have been able to get the IP number for the traceroute.

It is far more likely (especially if you use AT&T) that ICMP packets used for traceroute are being dropped.

23rd November 2012, 07:29 AM
The reason I had him use -I is because I've learned from experience that it's more reliable. I've seen regular traceroutes fail, then had them get through that way. If they're dropping ICMP ECHO requests they're really going out of their way to make diagnostics as difficult as possible.

23rd November 2012, 02:43 PM
What they are trying to do is make the internal AT&T network opaque.

I originally saw this happening while working at a government site - as soon as the tracroute left our networks it stopped. And restarted as soon as it left AT&T networks. Everything inside the AT&T network was lost.

And it did make things very difficult to diagnose problems. Fortunately for that site, the networks connected to DISA networks, then connected to AT&T.

DISA has a very big hammer to make AT&T fix problems...fast.

29th November 2012, 07:00 PM
Thank You for help. I tried another thing:
I borrowed the router of my neighbour.
Now everything is fine.
The router is guilty.
Now everything is fine.
Thank You for Your help.

Should I ask another question about Firefox here in the thread
or should I close the thread and should I start a new thread?