nanog mailing list archives

Re: CNAME records in place of A records


From: Rob McEwen <rob () invaluement com>
Date: Sun, 8 Nov 2020 20:01:12 -0500

On 11/8/2020 7:10 PM, Matt Palmer wrote:
On Fri, Nov 06, 2020 at 05:07:26AM -0500, Dovid Bender wrote:
Sorry if this is a bit OT. Recently several different vendors (in
completely different fields) where they white label for us asked us to
remove A records that we have going to them and replace them with CNAME
records. Is there anything *going around* in the security aranea  that has
caused this?
The closest thing to a *security* issue I can think of is IP agility in the
face of DDoS attacks -- most booter-style attacks are dumb as rocks, and
null-routing the target IP and moving all the customers on that IP to
another one is the easiest solution.

However, there are many *other* great reasons to get customers to CNAME onto
their SaaS vendors, including:

* No need to coordinate routine renumbering events;
* IPv6 support;
* CAA record (SSL cert issuance) support; and
* no doubt a bunch of other reasons I've forgotten for the moment.

Basically, if you sign up for a SaaS that uses your own domain and they
*don't* give you a CNAME target to point at, I'd be very cautious, because
they're either *very* new to the game, or they're probably also
operationally deficient in a lot of other areas, too.

- Matt


except - don't forget that the root of a domain (that domain without "www." or any other label) - cannot have a CNAME as the "A" record - fwiw...

--
Rob McEwen, invaluement

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