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-   -   Slack64 14 Can't connect to website sub domains (intermittent problem) (http://www.linuxquestions.org/questions/slackware-14/slack64-14-cant-connect-to-website-sub-domains-intermittent-problem-4175437561/)

nekopa 11-17-2012 07:29 AM

Slack64 14 Can't connect to website sub domains (intermittent problem)
 
Hi all,
I am having a strange problem which crops up now and then. I am connected to the internet, and can reach websites ok, but sometimes I can't get through to subdomains. For example, if I browse the NY Times site, I get all the info on the main page (nytimes.com) but with no formatting because the css for it is on a subdomain (css.nyt.com). Other sites which have content on subdomains come up "Server not found" (e.g. safaribooksonline.com is fine, but I can't access my.safaribooksonline.com)

Sometimes if I open a terminal window and ping the site or do an nslookup on it, it works, and then if I try to browse the site again it will work. But at other times ping can't find the site, and nslookup returns this error:

nslookup css.nyt.com
;; Truncated, retrying in TCP mode.
;; Connection to 192.168.1.1#53(192.168.1.1) for css.nyt.com failed: connection refused.

I have tried various browsers (firefox, opera, konqueror, lynx) and I am fairly sure it is not my wifi router and other computers in the house work fine (iPad, windows machine, and this laptop when I boot into windows)

So where should I start looking to find out what is going on?

(my laptop is an Acer 5542g, 4GB ram, 500GB HDD, ati mobile radeon graphics card, dual-booting win7 and slackware64 14 using lilo and EasyBCD)

Cheers for any ideas

freelinuxtutorials 11-17-2012 08:49 AM

seems like a DNS config?what's your /etc/resolv.conf ?

nekopa 11-17-2012 11:17 AM

Here it is:

# Generated by NetworkManager
nameserver 192.168.1.1


Why would this make the problem come and go?

Just to add more info: The problem comes and goes even without a reboot. When I started this thread, I couldn't get through to any subdomains, now they are working again.

nekopa 12-09-2012 12:51 PM

I found that appending this to the end of resolve.conf fixed the problem:

nameserver 208.67.222.222
nameserver 208.67.220.220

These are the domain servers from the openDNS free dns servers.

Apparently the problem was that if the UDP packets are too large, the system tries to switch over to TCP, but my router doesn't have DNS over TCP setup. The reason windows is fine with the situation is that it ignores the fact that UDP packets are too large and tries to go with the info it has received anyway.


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