Subject: Re: [dnsext] Re: DNS Proxy Implementation Guidelines - draft-ietf-dnsext-dnsproxy-01

From: "W.C.A. Wijngaards" <[email-masked]>
Date: Tue, 03 Feb 2009 13:12:47 +0100

Do implementations in the various client devices support short DHCP
lease times?

I think in a typical customer scenario, the devices boot within seconds
of one another.  Giving a resolver address in DHCP makes the customer
device at least try to send DNS queries to the proxy - and most
importantly have a timeout on that, show some blinking icon that it is
busy connecting.  When the WAN goes up, the proxy can deliver those
queries - I guess the proxy also has resends and timeouts.  After the
WAN goes up the reply is sent from the proxy (cannot route that reply
since the client device does not yet know the upstream DNS server it
came from).

If the client device got no DNS address, it would likely show an instant
failure (network not available or something) to the user.

So with the DNS proxy the edge router starts supporting DNS usage about
one second (or more if longer timeouts) before the WAN goes up, from a
user-experience point of view.

Best regards,
   Wouter

Ralph Droms wrote:
> Yes, no DHCP and link-local addresses are another possibility.  However,
> there may be other information to be delivered to the clients via DHCP,
> and some hosts/applications may not do well with a switch from
> link-local to routable addresses once DHCP actually runs.

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