On Mon, 27 Apr 1998, John Viega wrote:

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"John Viega" jtv2j@cs.virginia.edu wrote:

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1. DNS lookup can be slow. People want instant feedback.

People also want correct operation. Seriously, how long can a DNS lookup take? We're talking about subscribing to a mailing list. This is not an operation one does dozens of times a day. If it takes an extra 15 seconds, who cares?

I've seen it take several minutes when a DNS server is quite loaded. I frequently see lookups that take 10-20 seconds. The vast majority of users are typing in the correct thing anyway, and don't want to have to wait around. I'd prefer to catch the most common stuff, and give a speedy response saying, "If you don't get mail from us soon, try again, because we couldn't send mail to your address".

(I'm in the middle of something or i would have responded to several of the items going around at the moment, but i thought i'd chime in on this one immediately. I had also thought about querying the dns to do the address validation, but my gut feeling is that we can't assume we'll be able to do that everywhere in a portable way. I don't even know that we can presume that dns is used everywhere that might run mailman - they might use another name service, like nis/nis+, to deliver global host resolution to individual hosts at the site...)

(ken)