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https://issues.apache.org/jira/browse/TS-4403?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15265496#comment-15265496
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ASF GitHub Bot commented on TS-4403:
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Github user sudheerv commented on the pull request:
https://github.com/apache/trafficserver/pull/609#issuecomment-215995836
In the HTTP equivalent, returning stale data on error is not
stale-while-revalidate (SWR); it is a somewhat related, but, independent
feature called stale-if-error (SIE).
> HostDB's "stale while revalidate" doesn't span failed DNS lookups
> -----------------------------------------------------------------
>
> Key: TS-4403
> URL: https://issues.apache.org/jira/browse/TS-4403
> Project: Traffic Server
> Issue Type: Bug
> Reporter: Thomas Jackson
>
> Right now if you set stale_while_revalidate hostdb will return the stale
> record while waiting on the DNS lookup. In the event that you have the DNS
> timeout set low (lets say 1 second) and the DNS server times out (lets say
> due to an outage of your resolver) then ATS will start replacing all of your
> stale entries (which were working) with error timeout entries (which are
> empty)-- which is bad.
> The stale while revalidate configuration should serve stale records until a
> valid response from DNS comes back-- the patch here should be relatively
> simple, just a bit of a nuisance to test since DNS requires port 53 ;)
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