> I  have  a  proven,  software-only  solution  that  removes  a  dead
> gateway's  A  record  from  the gateway's record set. This adds some
> intelligence  to  the  dumb  load  distribution,  but  is  still not
> intelligent load balancing.

There's  also  a  proven,  software-only  solution already built in to
Windows.  An  appropriately  configured  Windows  client  can  trigger
self-registration  via  DDNS  every 30 seconds, while you scavenge old
records  on  the server side every 60 seconds (or however granular you
want to get with it).

Unless  you  get  sub-second  granularity,  though,  any polling-based
solution  using DDNS or any other kind of remote ping/port check + DNS
update   stands   some   chance  of  message  deferral,  and  if  it's
unacceptable  to  have  n  number  of  messages (peak n will depend on
site-specific  average  msgs  per  polling period, of course, and this
might  be very close to zero) have to wait an entire queue cycle to be
retried,  there  are  more  robust  choices,  still  not requiring any
third-party software:

·   network   load  balancing,  allowing  for  traffic-sensitive  load
balancing and failover

·  a  fake  DNS  root, using the MX algorithm for standard round-robin
load balancing plus failover

I  have  taken  to  using NLB in most such installations and no longer
deal  with  either  of  the  DNS-centric  options,  but  they  do have
considerable effectiveness and should be evaluated before opening more
complex cans of worms like NLB.

--Sandy


------------------------------------
Sanford Whiteman, Chief Technologist
Broadleaf Systems, a division of
Cypress Integrated Systems, Inc.
e-mail: [EMAIL PROTECTED]

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