W3C home > Mailing lists > Public > ietf-http-wg-old@w3.org > January to April 1996

Re: (DNS) consensus wording

From: Koen Holtman <koen@win.tue.nl>
Date: Mon, 1 Apr 1996 10:25:49 +0200 (MET DST)
Message-Id: <199604010825.IAA04820@wsooti25.win.tue.nl>
To: "David W. Morris" <dwm@shell.portal.com>
Cc: koen@win.tue.nl, jg@w3.org, http-wg%cuckoo.hpl.hp.com@hplb.hpl.hp.com
X-Mailing-List: <http-wg@cuckoo.hpl.hp.com> archive/latest/131
David W. Morris:
>It is my understanding that MUST and SHOULD are defined terms and
>strongly encouraged is not as far as RFCs are concerned.

Yes.  `strongly encouraged' seems to be a HTTP invention.  I don't see
this as a real problem, but it you would rather see SHOULD, that is
fine with me.

> Thus, I
>offer the following editorial alternative to Koen's suggestion (which
>I endorse):
>  If a client caches the result of a DNS lookups, it should observe the
>  TTL (Time To Live) reported by the DNS server. If the TTL value is
>  not available, the client must not cache the result of a DNS lookup
>  for longer than XX minutes. In either case, the client must immediately 
>  discard a name lookup result if a network error occurs when using the 
>  result to initiate a connection.

Your version looks OK to me.  

I have no real rationale for my XX=10 minutes, other than that it
seemed like a good enough XX to allow load balancing between mirrors
through dynamic DNS remapping.  Too high a value for XX (like the DNS
worst case default, if such a thing exists) would not sufficiently
encourage client authors in making code to get the real TTL.

>Dave Morris

Received on Monday, 1 April 1996 09:26:37 UTC

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