Codebase for my homepage.
git clone git://vcs.sapka.me/michal-sapka-me
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commit 519994cfdf82869610fbd09fa5bc1cbe8cd1f848
parent 2d409017937e0039965ce24cf38d0f584a05fa02
Author: MichaƂ Sapka <michal@sapka.me>
Date:   Sun, 15 Jan 2023 17:46:43 +0100

feat: dns error article

Acontent/2023/wildcard-mx-and-a-dns-record-conflict.md | 24++++++++++++++++++++++++
1 file changed, 24 insertions(+), 0 deletions(-)

diff --git a/content/2023/wildcard-mx-and-a-dns-record-conflict.md b/content/2023/wildcard-mx-and-a-dns-record-conflict.md @@ -0,0 +1,23 @@ +--- +title: "Wildcard Mx and a Dns Record Conflict" +category: "blog" +date: 2023-01-15T17:43:42+01:00 +draft: false +tags: ['dns', 'mx-record', 'a-record', 'email'] +--- + +A random problem I've just encountered by discovering that my email is broken. You can have a wildcard MX record (*.domain), which will handle all subdomains not defined by other records. + +>>> A common + mistake is thinking that a wildcard MX for a zone will apply to all + hosts in the zone. A wildcard MX will apply only to names in the + zone which aren't listed in the DNS at all. +>>> [RFC1912](https://www.rfc-editor.org/rfc/rfc1912) + +So, in this case, an A record for test.domain will break the email for test@domain. Solution: add a dedicated MX record for this domain (MX test.domain) with the same value as the wildcard. Now, even if the wildcard one is ignored, the client will fall back to the new record. + +``` +*.domain MX 10 addr +test.domain A 10 adddr2 +test.domain MX 10 addr +``` +\ No newline at end of file