> Are  you saying the QM has its own recursive/smart resolver? because
> some Imail machines don't have access to a resolving, external DNS?

I  believe  Christian  is  referring  to the Win2K+ DNS cache service,
which  is tied to the underlying OS resolver. IMail implements its own
DNS  resolver,  which of course uses the OS TCP/IP stack, yet does not
tap into the OS DNS cache.

Neither  the Windows nor the IMail resolver, with or without their DNS
caches  enabled, themselves perform recursion. They just set the usual
recursion   flag   in  their  requests.  (Since  they  then,  somewhat
abnormally  for  resolvers,  manage  TTLs  and an in-memory cache, you
could  perhaps  liken  them  to  a caching DNS server that solely uses
forwarders.)

> How could someone run an mail server without an external DNS?

I  think  "local"  here refers to either a LAN-speed DNS server on the
local  net,  or  a  locally-hosted  daemon  on  the  loopback address.
Christian means to distinguish this from those who use their ISP's DNS
servers,  likely  due  to  a  lack of in-house expertise, yet who have
insufficient  bandwidth  relative  to their DNS demands. This may seem
like  a  rare  situation  (given some of the associative relationships
between mail load and IT staffing), but it's out there.

--Sandy


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

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