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reply to cghh

Re: Redirection tool preemption

said by cghh:

BTW, with E-mail, it is true that SMTP servers will first do a MX lookup, but if that fails, they will then do an A lookup, which will never fail with this corrupted DNS.
That is the exact problem that occurred when Verisign (who runs roots for .com) tried this very same thing a couple of years ago.

It was on a much larger scale, of course, since it applied to everyone everywhere, but email problems were rampant. Instead of immediate bounces for improper domains, suddenly every email domain appeared valid and would sit on queue for days before bounces would happen. Millions of sites were affected, and eventually most large ISPs had to override the A record and put those IP addresses on their ignore lists.

There are undoubtedly thousands of other applications that depend on NXDOMAIN responses being properly returned on invalid domains.

HTTP is not the Internet, and ISPs need to remember that.