Hostnames in backend definition...

Hettwer, Marian mhettwer at
Wed Dec 14 11:09:37 CET 2011

Hi there,

On 13.12.11 18:22, "david raistrick" <drais at> wrote:

>I've sort of been threatening to get one of my team to work up a patch to
>varnish to do some DNS sanity, but until it actually becomes a major
>blocker for us (we have other workarounds in place - like not using ELB
>and using internal dynamic config re-generators) I can't get the resource
>to do it...

Does varnish cache DNS entries forever and does the dns lookup only once
at startup time?

If so, why would it do that?
The initial DNS answer would include a TTL, indicating how long the record
is valid.
Proper behaviour would be to do another DNS questions, as soon as the TTL
is not valid anymore.

Not behaving correctly in DNS is bad.

Perhaps someone could enlighten me why one would go that road?

(more or less the same behaviour is known to me by java, and I hate it.
Squid is doing the same too. And it's a pain).


More information about the varnish-misc mailing list