BIND 8.1.2 on solaris7 X86 Secondary DNS server

[Mark_Andrews at isc.org]

> Mark_Andrews at isc.org wrote:
> > 
> >         We fixed a number of DoS issues with BIND 8.2.2 this may be one
> >         of them.  It may also just be resource starvation.  BIND does not
> >         behave well in an envirionment where there is swapping / paging
> >         occuring.
> > 
> >         Mark
> > 
> 
> 
> Please explain in a bit more detail, what you mean by the above. I run
> under Solaris 2.x which swaps/pages regularly and have noticed
> degradation in my name services. I would like to know whether or
> not your observations apply to my situation.

	In general there is no locality of reference between seqential
	queries to a nameserver or between when the internal tree is
	stored and the data hanging off it.  This results in almost the
	worst possible memory access patterns for a VM subsystem that
	is short of physical memory as the page that was just freed is
	the one likely to be needed next.

	On top of that names periodically has to walk the entire tree
	to free up resource records that have expired.  The creates a
	working set of pages which encompass the whole memory image.

	If there is not enough memory to hold the whole image in physical
	memory at one time performance goes through the floor.

	Named is designed to handle thousands of queries per second.  You
	don't get that speed unless most of the queries are answered from
	memory.

	One of BIND 9 design goals is to improve this behaviour.

	Mark
> 
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--
Mark Andrews, Internet Software Consortium
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: marka at isc.org