From: Anand Buddhdev <anandb@ripe.net>
To: "@lbutlr" <kremels@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 listPlease visit https://lists.isc.org/mailman/listinfo/bind-users to unsubscribe from this list
bind-users@lists.isc.org
https://lists.isc.org/mailman/listinfo/bind-users _______________________________________________
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.
-----Alkuperäinen viesti-----
Lähettäjä: bind-users <bind-users-bounces@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?
From: Anand Buddhdev <anandb@ripe.net>
To: "@lbutlr" <kremels@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.
| Sysop: | DaiTengu |
|---|---|
| Location: | Appleton, WI |
| Users: | 910 |
| Nodes: | 10 (0 / 10) |
| Uptime: | 210:39:52 |
| Calls: | 12,116 |
| Calls today: | 1 |
| Files: | 186,504 |
| Messages: | 2,226,618 |