[Unbound-users] Troubles with using Round-Robin balancing.

Maik Zumstrull Maik.Zumstrull at rz.uni-karlsruhe.de
Mon Apr 19 09:06:51 UTC 2010

Pavel wrote:

> But unfortunately I've found that round-robin balancing don't really
> works via unbound.

It doesn't always shuffle multiple A-Records around when it returns
them, but it does return all the records for round-robin names. Looks
compliant to me.

> It receives first reply from primary server, puts it in the cache and
> then returns it always until the TTL is expired.

So...it does exactly what it's supposed to be doing?

Does the name you're querying use real round-robin, that is, it returns
multiple A-records? Or does it return one record only, but a different
one every time you query? In that case, that zone is broken. That is
*not* what round-robin means, they're doing it wrong. They need to
either return all relevant A-records, or at the very least reduce the
TTL to only a few seconds to make sure their pseudo-round-robin isn't
killed by legitimate caching on recursors.

> So, I think that it's a good idea to implement an availability of
> 'no-cache' option which will affect to defined zone.
> There are enough of situations when some zone shouldn't be cached.

First of all, no, not really. Secondly, in this case that zone should
be announcing a very low TTL, not expect recursors to magically know
not to cache entries, even though they're announced as cacheable.

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