This is Paul Vixie's response on this, when I asked him for verification:
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this bug has been reported over and over again for a dozen years. it's
odd to have to keep fixing it-- i fixed it in bind4 and bind8 when theo
de raadt offered me his random number generator to use. bind9 should've
used that same one but apparently didn't. note that with this fix, the
difficulty in poisoning someone's cache rises from "a few tens of
seconds"
to "a few minutes". it's a 16-bit field. not a lot of room for
randomness or unpredictability. only DNSSEC, a protocol change, fixes
this problem, which is fundamentally a protocol problem. but since folks
just won't leave it alone and keep on reporting it year after decade, we
will keep on improving our random number generator for this dinky little
16-bit field. i just wish the reporters wouldn't be so smarmy and self
congradulatory about it. it's not like this hasn't been reported, and
fixed, many times by many others.
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Gadi.