[Cialug] nslookup works but ping cannot resolve

[David Champion]

Does dig return different results than nslookup for your internal DNS 
queries?

-dc

Paul Gray wrote:
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> Nathan Stien wrote:
>   
>> On Feb 8, 2008 12:32 PM, Paul Gray <gray at cs.uni.edu> wrote:
>>     
>>> I heard the suggestion, but not a confirmation, that /etc/hosts should
>>> be sanity checked.
>>>       
>> It's a fresh install of ubuntu 7.10.  /etc/hosts contains the
>> definition of localhost and the standard IPv6 symbols.
>>
>>     
>
> Then, the course of diagnostics that I would suggest:
>
> # apt-get install tcpdump strace
>
> bring up four terminals, and issue, respectively:
>
> A) # tcpdump -x -s0 2>&1 | tee /tmp/tcpdump.out
>
> B) # strace -f ping host_that_I_cannot_get_to 2>&1 | tee /tmp/strace.out
>
> C) # iptables -L
>    # iptables -t nat -L
>    # route -n
>    # arp -n
>
> D) (Open on the remote host)
>    # tcpdump icmp
>
> Search the /tmp files for the root of the problem; look for icmp
> echo-requests and echo-reply's.  In the end, the above should give you a
> dead-on way of diagnosing the root of the problem...or at the very least
> something to dump to folks out-of-band to resolve the issue.
>
> Hope that helps.
>
> - -PG
>
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