dns resolving apparently not working

**N-t-F** · January 3rd, 2012

Hello,

I've just installed Xubuntu 11.10 on a new PC without any issue, then I have configured the network, but dns resolution apparently doesn't work. Here's what I did:

1) Uninstalled network-manager to prevent it from putting its nose into the manual configuration:

Code:

apt-get remove network-manager network-manager-pptp

2) edited /etc/network/interfaces to get:

Code:

auto lo
iface lo inet loopback

auto eth0
iface eth0 inet static
address 192.168.31.150
netmask 255.255.255.0
gateway cerbere

This seems to work so far because I can at this point ping both my file server and my gateway.

3) Edited /etc/environment to add:

Code:

http_proxy="http://{my.proxy.address}:8080/"
ftp_proxy="ftp://{my.proxy.address}:8080/"
https_proxy="https://{my.proxy.address}:8080/"

4) Edited /etc/resolv.conf to get:

Code:

nameserver 1.2.3.4 5.6.7.8

(with actual triple checked DNS IPs, obviously

)

Then, when I try to access Internet, I get an error message explaining the name of my proxy is unknown. Similarly, when trying to use:

Code:

apt-get update

it fails, saying that something unexpected happened while trying to find my proxy because no address was associated with it. Looks like a DNS issue to me (or a proxy one, but other computers on the same network do access Internet and repository).

I guess it may be a simple problem, but I just don't see it right now, so I would be grateful for any hint you could have. By the way, it's the configuration I've been using with (Gnome)Ubuntu 10.04. for more than a year now, so I wonder if something just changed between versions regarding basic network configuration.

Thank you.

(And happy new year!

)

**sj1410** · January 3rd, 2012

Edited /etc/resolv.conf to get:
Code:
nameserver 1.2.3.4 5.6.7.8

it should be

nameserver 1.2.3.4
nameserver 5.6.7.8

**N-t-F** · January 4th, 2012

Thank you for answering.

I thought both syntax gave the same result. But I've edited out my file as you suggest, with no change, unfortunately.

**sj1410** · January 4th, 2012

looks like name resolution issue. try using ip address instead of proxy server name. to check if the name resolution is working properly try the dig command

Code:

dig www.google.com

**N-t-F** · January 4th, 2012

Okay, this actually helped. The answer to the command said the name server could not be reached, so it was really a networking problem, not just a DNS one. The most obvious reason I could imagine was that I couldn't get out of my own network, so I tried to tweak my /etc/network/interfaces file a bit. What finally worked was to replace:

Code:

gateway cerbere

with

Code:

gateway 192.168.31.5

This looks a bit weird for two reasons:
1) pinging cerbere works (ie: the system can translate it to an IP address, taking it from /etc/hosts)
2) "gateway cerbere" in /etc/network/interfaces works just fine with my 10.04 systems (using the same /etc/hosts).

Anyway, it now appears to work.

Thank you again.