Comment 9 for bug 458999

Strictly speaking even hostname lookup failures are recoverable
but may need special admin actions (/etc/hosts or DNS setup) to recover.

Or in a home-network a hostname lookup failure might be even
only a temporary failure because the local machine which acts
as DNS server might be currently down (e.g. one of those small
router boxes for home or small local network use).

Therefore it is my personal opinion to loop for some time even
in case of errors like hostname lookup failure, provided:

a)
The backend opuputs meaningful error messages via stderr like
"Hostname lookup 'does.not.exist' failed. Retry in 5 minutes."
so that the user who submitted the print job is informed
and can decide if he likes to cancel the whole job or
if he likes to contact the admin (who is perpaps he himself
in a home network) to get the issue fixed.

b)
There is a reasonable sleep time between each retry
for this particular case of error (e.g. 5 minutes here).

c)
Optionally there could be a limited number of retries.
E.g. after one week it does probably make no sense
to retry regardless what the reason of the failure is.