Host sometimes Succeeds with Empty Output

Sten Carlsen stenc at s-carlsen.dk
Fri Sep 14 15:05:59 UTC 2012


Timeouts along the chain?

On 14/09/12 16:48, Martin McCormick wrote:
> I needed to delete the CNAME record of
> physicscourses.okstate.edu. After the deletion, the host command
> would silently exit successfully as if this alias was still
> there. I have seen this behavior a few times before but am not
> sure what triggers it as one normally gets the usual "host
> whatever.com not found" and host exits non zero.
>
> 	If I specifically command
>
> host -tCNAME physicscourses.okstate.edu
>
> I receive that there is no CNAME record named
> physicscourses.okstate.edu but host still exits as if successful
> in finding it.
>
> 	There is a www.physicscourses.okstate.edu CNAME record
> and this maybe has something to do with the unusual reply.
>
> 	I had a script that was using the return status of host
> and it works great guns unless you run in to this situation in
> which it thinks the alias still exists. This causes an infinite
> loop because it is waiting for the lookup to fail which it
> normally does as soon as the nsupdate command's results
> propagate out in a very short time.
>
> 	I did check our zone for any other records for
> physicscourses.okstate.edu which, of course, would be an error
> after having had a CNAME record of that name, but there wre
> none.
>
> Thanks for any light you can shed on why host still thinks there
> is something there.
>
> Martin McCormick
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-- 
Best regards

Sten Carlsen

No improvements come from shouting:

        "MALE BOVINE MANURE!!!"

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