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DNS problem? web lookups very slow


Guest Adriano
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Guest Adriano

Until recently (December, when I went on holidays), my net connection was working fine (It's Alice ADSL in Italy, if anybody knows. ADSL through pppoe, an ethernet Siemens Gigaset modem). Now I'm back, and the service is much slower in a particular way. I notice everything takes a long time doing dns lookups (after that, the pages or the downloads are fast). For example, if I ping google.com, it takes a few seconds to find the address. If I ping the IP, it does it immediately.

 

I checked /etc/resolv.conf, and the servers provided automatically are there. What can be the problem?

 

I recently (three days ago) installed Ubuntu on another HD, and it has the same problem. Windows XP on the other hand is working fine (checked today). It feels as if the provider changed something to the connection and Linux is taking it the wrong way, but what could it be?

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have you tried using some alternative dns-servers already? i know of a similar thing from a friend of mine with suse 9.0. once he changed the dns-servers, everything was fine again.

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Anyway, where do I find a couple of free DNS server IPs? I tried googling, but all I get are the services. I'll try with my addresses from zoneedit.

 

I've noticed that MDK seems to put 127.0.0.1 as the first entry in /etc/resolve.conf. If it's there, try removing it and see if that helps.

 

Jeremy

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Guest Adriano

nope, only the two IPs my provider sends. They are repeated, though, like this:

 

nameserver 85.37.17.10

nameserver 151.99.125.1

nameserver 85.37.17.10 # ppp temp entry

nameserver 151.99.125.1 # ppp temp entry

 

I tried deleting them, but of course they are replaced at boot again.

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Guest Adriano

no, that made my connection to fail completely. I had to recreate a connection, but the problem persists (the DNS lookup problem). Are you sure those lines go into /etc/modprobe.conf?

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this does not seem to be an ipv6 problem. otherwise he also would have had the problem before, jeremy. so adding the lines you mentioned does not help here, i guess. ;)

 

i thought a bit about this matter and adriano, you are right, a dns-server change seems kinda weird but adding further dns-entries could help. try dns server from other service providers if you don't find any free ones (i need to check on them, too).

 

i still have two questions: have you done any updates recently to your system? doe you have these connection problems with all websites or only certain websites? if it happens only with some websites, i could imagine is that your dsl-connection in linux uses an mtu and mru package value that might be too high. the bad thing is: i don't know how to change these values in linux. only whith routers. :P

Edited by arctic
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okay, that leaves out an mtu/mru problem. have you tried already adding more dns-servers to your resolv.conf? you didn't give any answer to that till now.

maybe you wanna check some setting here http://www.dnsstuff.com/ or here http://www.ipv6tools.com/

 

you might want to test this sites dns-adress http://my.qwest.net/nav4/help/your_acct/dns_service.html

 

if it still does not work, i would suggest: contact your isp. maybe they changed anything and you need to adjust some of your system settings before everything goes well again.

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Guest Adriano

OK, I tried with the DNS servers in the page you linked, and it works again perfectly. At least, until the next time I reboot. Maybe I should do a script to re-add them to the file every time I boot up.

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