Vista: what your mom never told you

John Hascall john at
Thu Feb 21 20:58:53 UTC 2008

> So there are two things your mom never told you about Vista clients.
> One is that they might set the IP source address nonzero, and this is
> just fine so far as dhcpd is concerned...maybe not so fine as some
> folks' firewall rules or DHCP snooping equipment is concerned.
> The other is that Vista sets the 'broadcast bit' in the BOOTP header,
> which informs dhcpd that it is required to answer the client in
> broadcasts.  We've had some folks find their networks misdirect, drop,
> or just filter out broadcasts from the DHCP server.

   Is there a more classic example of Microsoft thinking?

   The use a (non-standard) extension of a standard (which was first
   done on a Mac!) whose purpose is to eliminate the need for the
   broadcast bit, and then they set the broadcast bit.


PS, they probably also have a patent pending on it :)

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