Why *can* cached DNS replies be overwritten?

[dot at dotat.at (Tony Finch)]

On Mon, 11 Aug 2008, Jay R. Ashworth wrote:
>
> Everyone seems to continue asking "why can poisoning overwrite already
> cached answer" and no one seems to be answering, and, unless I'm a
> moron (which is not impossible), that's the crux of this issue.

Add me to the list of baffled observers. As far as I can tell this
vulnerability to poisoning is mostly forbidden by the trustworthiness
ranking in RFC 2181.

Tony.
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