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From time to times I have to reboot my Ubuntu 11.04 remote desktop. Once it up and I run Cromium browser with many tabs (20 for example) dns server doesn't respond anymore. At beginning I suspected my ISP, so I replaced my /etc/resolv.conf with following values:

nameserver 208.67.222.222
nameserver 208.67.220.220
nameserver 8.8.8.8

The result is the same - I can't use browser for ~20 min. because names are not resolved, ping doesn't work either.

Any idea what is blocking?

Thomas Ward
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Dzidas
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  • When you say ping doesn't work either do you mean IPs also? Or just names? Can you ping 8.8.8.8? – Daniele Santi Jul 07 '11 at 11:49
  • I meant just names. During that time I'm able to connect remote machine and some services, like skype, are able to connect to internet (I suppose Skype use IP address). – Dzidas Jul 07 '11 at 12:17
  • did you try removing the first two values? For me, I completely removed my ISPs DNS entries, and hardcoded (and subsequently write-protected) my list of nameservers... I use 8.8.8.8 and 4.2.2.4 and they work fine. – Thomas Ward Jul 07 '11 at 13:05
  • The first two are OpenDNS entries, not my ISP. – Dzidas Jul 07 '11 at 13:09
  • regardless if they're your ISP, did you try removing them and just leaving nameserver 8.8.8.8 just to see what happens? i just ran a DNS lookup off of 8.8.8.8, so I know its functioning. – Thomas Ward Jul 07 '11 at 13:12
  • darn i wasnt fast enough to edit my last comment. regardless, try this and give us the output: dig @8.8.8.8 www.ubuntu.com – Thomas Ward Jul 07 '11 at 13:23
  • so I changed: cat /etc/resolv.conf nameserver 8.8.8.8 and then I ran this: sudo /etc/init.d/networking restart * Running /etc/init.d/networking restart is deprecated because it may not enable again some interfaces * Reconfiguring network interfaces... – Dzidas Jul 07 '11 at 14:09

3 Answers3

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Well, could really be a problem with your ISP DNSs and maybe they intercept DNS traffic and route it throurgh their servers...

Try a dig @8.8.8.8 www.ubuntu.com and see what happens.

Output should be like:

; <<>> DiG 9.7.3 <<>> @8.8.8.8 www.ubuntu.com 
; (1 server found) 
;; global options: +cmd 
;; Got answer: 
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 54464 
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0 

;; QUESTION SECTION: 
;www.ubuntu.com.      IN  A 

;; ANSWER SECTION: 
www.ubuntu.com.   497 IN  A 91.189.89.88 

;; Query time: 2307 msec 
;; SERVER: 8.8.8.8#53(8.8.8.8) 
;; WHEN: Thu Jul  7 14:23:41 2011 
;; MSG SIZE  rcvd: 48
Daniele Santi
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  • xxx@xxx:~$ ping www.google.com ^C xxx@xxx:~$ dig @8.8.8.8 www.ubuntu.com

    ; <<>> DiG 9.7.3 <<>> @8.8.8.8 www.ubuntu.com ; (1 server found) ;; global options: +cmd ;; connection timed out; no servers could be reached

     – Dzidas Jul 07 '11 at 13:28
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    Sounds like dns lookups are being blocked somewhere along the line. Can you ping 8.8.8.8? – Thomas Ward Jul 07 '11 at 13:53
  • x@x:~$ ping 8.8.8.8
    PING 8.8.8.8 (8.8.8.8) 56(84) bytes of data.
    64 bytes from 8.8.8.8: icmp_req=1 ttl=54 time=81.8 ms
    64 bytes from 8.8.8.8: icmp_req=2 ttl=54 time=31.9 ms
    64 bytes from 8.8.8.8: icmp_req=3 ttl=54 time=29.0 ms
    64 bytes from 8.8.8.8: icmp_req=4 ttl=53 time=29.4 ms
    ^C --- 8.8.8.8 ping statistics ---
    4 packets transmitted, 4 received, 0% packet loss, time 3004ms
    rtt min/avg/max/mdev = 29.084/43.069/81.809/22.394 ms
    x@x:~$ ping www.google.com
    ping: unknown host www.google.com     – Dzidas Jul 07 '11 at 14:13
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Try installing the dnsmasq package and configuring it to cache DNS for you. This should cut down on your DNS queries and may prevent whatever is blocking you from activating. It could be a DNS rate limit filter somewhere in your chain.

Your /etc/resolv.conf for dnsmasq should consist of 127.0.0.1. I am not sure if the current installer sets this up.

BillThor
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0

You can also use Google's open dns:

so could edit /etc/resolv.conf:

# Googles Public DNS

nameserver 8.8.8.8

nameserver 8.8.4.4

search localdomain

gare
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