Subject: (ngtrans) Re: ipv6-smtp-requirement comments?

From: "D. J. Bernstein" <[email-masked]>
Date: 26 Oct 2001 14:49:03 -0000

> If a site has IPv4/v6 dual stack reachability, the site SHOULD configure
> both A and AAAA records onto its MX hosts.  It will help both IPv4 and
> IPv6 senders to reach the site efficienlty.

I don't understand.

There is an obvious management cost in having both IPv4 and IPv6
addresses for a server. What exactly is the benefit?

The current (transition) situation is that some clients can't talk to
IPv6 servers. In this situation, every site needs an IPv4 server. What
exactly is the benefit of adding an IPv6 server?

The future (goal) situation is that every client can talk to IPv6
servers. In that situation, it will be safe to set up an IPv6-only site.
What exactly is the benefit of adding an IPv4 server?

---Dan

---

From: [email-masked]
Date: Mon, 29 Oct 2001 09:52:13 +0900

>addresses for a server. What exactly is the benefit?

	benefit is, you can make use of both IPv4 and IPv6 for email delivery.
	if you are dual-stacked and you would like to take advantage of both
	connectivities for email derlivery, you will want to configure A and
	AAAA for MX.

>exactly is the benefit of adding an IPv6 server?

	still, there are IPv6-capable servers out there.  you can deliver
	emails over IPv6 when you talk with them.  we will gradually transition
	to more IPv4/v6 dual stacked network, and delivery over IPv6 will
	become more frequent.

itojun