Many spammers send in addition to MX to A records, if available. Still, it is a good practice to not to publish an A record for the mail zone, if not specifically needed for something else. Of course if it points to somewhere else than the receiving SMTP server, not much harm done mail-traffic-wise.
Jukka -----Alkuperäinen viesti----- Lähettäjä: bind-users <bind-users-boun...@lists.isc.org> Puolesta Matthew Richardson Lähetetty: 9. heinäkuuta 2020 16:06 Vastaanottaja: bind-users <bind-users@lists.isc.org> Aihe: Re: Dumb Question is an A or AAAA record required? On a related issues there were (perhaps long ago) issues if the A record for a domain had an SMTP server on it, where email could sometimes be delivered to that A record rather than the MX. I had (again long ago: 10-15 years) actually seen this occur. Do people think that this problem could still occur these days? What sort of transient (presumably DNS) failure might cause an SMTP server to deliver to A rather than MX? Best wishes, Matthew ------ >From: Anand Buddhdev <ana...@ripe.net> >To: "@lbutlr" <krem...@kreme.com>, bind-users ><bind-users@lists.isc.org> >Cc: >Date: Thu, 9 Jul 2020 14:43:04 +0200 >Subject: Re: Dumb Question is an A or AAAA record required? >On 09/07/2020 14:21, @lbutlr wrote: > >> Given a domain that is hosted and used for email and web, is an A >> record for that domain actually required? > >It's not *required*. But see below. > >> That is, if bob.tld is hosted by example.com can you simply have >> >> NS ns1.example.com >> NS ns2.example.com >> MX mx.example.com >> >> www CNAME www.example.com >> >> Without specifying >> >> A 11.22.33.444 > >These days, many folk try to reach websites by typing just the bare >domain name without the "www" prefix. > >If a user types "bob.tld" into a browser, the browser will issue an >address lookup for "bob.tld", causing the resolver to ask for A and >AAAA records for "bob.tld". If you don't have an A record at the zone >apex, the browser will not get back any address and display an error >message for the user. An alert user might try "www.bob.tld" but most >users are likely to just give up. > >So while it's not *required* to have an address record at the apex, >it's good practice to have one. > >Anand >_______________________________________________ >Please visit https://lists.isc.org/mailman/listinfo/bind-users to >unsubscribe from this list > >ISC funds the development of this software with paid support subscriptions. >Contact us at https://www.isc.org/contact/ for more information. > > >bind-users mailing list >bind-users@lists.isc.org >https://lists.isc.org/mailman/listinfo/bind-users _______________________________________________ Please visit https://lists.isc.org/mailman/listinfo/bind-users to unsubscribe from this list ISC funds the development of this software with paid support subscriptions. Contact us at https://www.isc.org/contact/ for more information. bind-users mailing list bind-users@lists.isc.org https://lists.isc.org/mailman/listinfo/bind-users _______________________________________________ Please visit https://lists.isc.org/mailman/listinfo/bind-users to unsubscribe from this list ISC funds the development of this software with paid support subscriptions. Contact us at https://www.isc.org/contact/ for more information. bind-users mailing list bind-users@lists.isc.org https://lists.isc.org/mailman/listinfo/bind-users
