Subject: Re: On Scaling of DNS-SD

From: Keith Moore <[email-masked]>
Date: Wed, 31 Jul 2002 10:17:33 -0400

have you ever tested any of mDNS-ish solutions in real life?  it
        doesn't break anything.  it just works, and works great.
        if you want to give it a shot, try kame mdnsd (uses old mDNS draft)
        or revlookupd (draft-itojun-ipv6-nodeinfo-revlookup-00.txt).

have you ever tested any of these solutions with distributed applications,
where some of the nodes are using mDNS and others aren't?

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From: Bernard Aboba <[email-masked]>
Date: Wed, 31 Jul 2002 06:45:31 -0700 (PDT)

> 	or revlookupd (draft-itojun-ipv6-nodeinfo-revlookup-00.txt).

I think that Keith is referring to situations in which the DNS
configuration mechanism goes down sporadically. For example, where there
is high packet loss or broken connections or where the DNS discovery
mechanism is sporadic. In that case, some nodes may be configured with a
DNS server and others may not be.

I think that this argument doesn't relate to mDNS so much as to the
importance of resilience in service discovery/configuration.

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From: Keith Moore <[email-masked]>
Date: Wed, 31 Jul 2002 10:50:01 -0400

> DNS server and others may not be.

that's one way it can happen.  there are others.

in general one should not assume that every node in an application is 
configured consistently with every other node.    nor is it reasonable
to assume that nodes using mDNS are on an isolated newtork.  connection
to and configuration of DNS, and connections to other networks  can
exist independently of one another.

there's also a problem with the answers to DNS queries (as seen  by 
a node of an application) changing over time depending on whether
mDNS or DNS is being used at that particular time.

Keith