On Thursday, February 06, 2003 2:48 PM, Richard Kettlewell wrote:
I think the next step is to determine if Mozilla is even sending any DNS queries. As root, this command:
tcpdump -n port 53
will report any DNS packets appearing on your ethernet.
Do a ping with this running first; you'll see the kind of thing that ought to be happening (there ought to be a request and a response).
On console 1: ian@suzy:~> su - Password: suzy:~ # tcpdump -n port 53 tcpdump: listening on eth0 15:55:31.225452 192.168.1.131.1026 > 194.168.4.100.53: 22127+ A? www.alug.org.uk. (33) (DF) 15:55:31.247546 194.168.4.100.53 > 192.168.1.131.1026: 22127 1/3/0 A 199.254.168.73 (138) (DF) 15:55:31.568373 192.168.1.131.1026 > 194.168.4.100.53: 22128+ PTR? 73.168.254.199.in-addr.arpa. (45) (DF) 15:55:31.823014 194.168.4.100.53 > 192.168.1.131.1026: 22128 1/2/2 (156) (DF) 15:55:32.570950 192.168.1.131.1026 > 194.168.4.100.53: 22129+ PTR? 73.168.254.199.in-addr.arpa. (45) (DF) 15:55:32.589337 194.168.4.100.53 > 192.168.1.131.1026: 22129 1/2/2 (156) (DF) 6 packets received by filter 0 packets dropped by kernel
While on console 2: ian@suzy:~> ping www.alug.org.uk PING www.alug.org.uk (199.254.168.73) from 192.168.1.131 : 56(84) bytes of data. 64 bytes from carpediem-it.co.uk (199.254.168.73): icmp_seq=1 ttl=237 time=255.296 msec 64 bytes from carpediem-it.co.uk (199.254.168.73): icmp_seq=2 ttl=237 time=250.195 msec --- www.alug.org.uk ping statistics --- 2 packets transmitted, 2 received, 0% loss, time 1011ms rtt min/avg/max/mdev = 250.195/252.745/255.296/2.599 ms~>
Then try to visit a website through Mozilla and see what you see. Paste it all into another message to this list if you have trouble interperting it.
On console 1: suzy:~ # tcpdump -n port 53 tcpdump: listening on eth0 0 packets received by filter 0 packets dropped by kernel
While on console 2 I start Mozilla and type http://www.alug.org.uk and I get the "Alert: www.alug.org.uk could not be found. Please check the name and try again" error message.
That said if Mozilla has randomly decided to stop doing DNS lookups I'm not sure what you can do about it, other than possibly reinstalling Mozilla.
Hmmm... What I suspected. I thought it would be worth mentioning this problem on the list first though just in case anyone had come across the problem before and knew how to fix it.
Thanks for all your help,
Ian.