Is there a way to invalidate a cached item on multiple varnish servers at once?

[Rainer Duffner]

Am Mon, 30 Sep 2013 13:44:34 -0700
schrieb James Pearson <james at ifixit.com>:

> Excerpts from Rainer Duffner's message of 2013-09-29 13:45:51 -0700:
> > Hi,
> > 
> > suppose you've got a couple of load-balanced varnish-servers, is
> > there a way to have an item removed from the cache on multiple
> > servers at the same time?
> 
> How small of a window do you need?  I'd probably just fire off a
> PURGE request to each server, but that'd give a few seconds where
> some servers would have a cache entry and others would not.

It's not a question of a certain time-window.
More a question of transparency.
E.g. in Drupal, you can only enter a single IP.

It's unreasonable to assume a user would be able to issue a purge on a
2nd (or 3rd) server himself - as he may not know the IPs of these
servers anyway.