[ILUG] Broken DNS

[Gareth Eason]

	   Hi,

	dig is the seminal tool for testing all things DNS related. It's simple
to use, but very powerful.

	Also, take a look at the output of 'cat /etc/resolv.conf' and see if
you can ping the DNS servers contained therein, and whether they
actually answer DNS questions.

	e.g. for my laptop at home:
eason at lynx:~$ cat /etc/resolv.conf
# Generated by NetworkManager
nameserver 192.168.0.1

eason at lynx:~$ dig blog.signal2noise.ie @192.168.0.1

; <<>> DiG 9.5.0-P2 <<>> blog.signal2noise.ie @192.168.0.1
;; global options:  printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 54941
;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 3, ADDITIONAL: 0

;; QUESTION SECTION:
;blog.signal2noise.ie.		IN	A

;; ANSWER SECTION:
blog.signal2noise.ie.	3600	IN	CNAME	www.signal2noise.ie.
www.signal2noise.ie.	3600	IN	A	213.239.194.114

;; AUTHORITY SECTION:
signal2noise.ie.	439	IN	NS	ns1.signal2noise.co.uk.
signal2noise.ie.	439	IN	NS	ns2.signal2noise.co.uk.
signal2noise.ie.	439	IN	NS	ns3.signal2noise.co.uk.

;; Query time: 80 msec
;; SERVER: 192.168.0.1#53(192.168.0.1)
;; WHEN: Tue Apr 21 00:38:56 2009
;; MSG SIZE  rcvd: 144

	So this confirms my experience that DNS in my home LAN works (with the
minor caveat that I've just noticed it only returns A records for IPv4
by default, and I have to ask it specifically for AAAA records for IPv6.
Must look at improving that :)  )

	Hope this helps.

	Best regards,
	-->Gar


Paul O'Malley - gnu's not unix - wrote:
> Philip Creevy wrote:
>> Gooday all
>> I have a friend using Ubuntu 6.?? and he is having DNS
>> problems, could someone point me at a good howto and what tools I can
>> use to poke the problem.
>> I can ping any IP address and browse IP addresses
>> but cannot resolve names.
>> A different computer connected to the same ethernet cable
>> works.
>>
>> Regards
>> Philip
>>
>>
> 
> if it is a dhcp client machine (i.e. gets a dynamic ip from a router)
> then you could be really lazy and type
> 
> close web browsers
> 
> sudo dhclient
> 
> open web browsers should work
> 
> if not
> cat /etc/resolv.conf
> 
> check if the name servers it is looking up are sensible
> 
> also note that 6.10 is out of support
> 
> and 6.06 is about to fall out of favour for desktops
> (3 years from release) and has about two years left for server only mode
> 
> poke:
> 
> http://ubuntuforums.org/archive/index.php/t-344212.html
> 
> an upgrade is in order
> 
> P.
>