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I would like to understand if multiple TXT records for the same subdomain are ok or could lead to issues. In particular, we have the requirement for one SPF record and one Google Domain Verification record on the root domain.

In AWS Route 53 they explicitly support this in the following way:

Enter multiple values on separate lines. Enclose text in quotation marks. Example: "Sample Text Entries" "Enclose entries in quotation marks"

This way a single TXT field can contain both the SPF and Google Domain Verification records.

When I asked name.com on the other hand they suggested to add two separate TXT records as the Route 53 method is not supported.

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The way described is the way you create multiple records on Route 53.

Entering two values in the textarea separated by a newline will result in two distinct records in the DNS. This is why Amazon call it a "record set" - it is a set of records.

  • 3
    The OP cannot be the only person making this mistake; it's really not obvious. There is no sensible error message that explains this, when you try to add a second TXT record the 'more obvious' way. – Bobby Jack Jan 9 '18 at 9:50
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Michael is correct in regards to where your point of confusion is coming from. I'm going to proceed with my usual stuffiness and answer the larger question for those who might happen by from a Google search.

  • Multiple TXT records are completely legal per the DNS standards.
  • Multiple TXT records implementing a specific standard can potentially be illegal, but only within the scope of that one standard.
  • Given the need for multiple standards to coexist and play nicely with other TXT records that share a given name, conflicts are unlikely to happen. It is certainly unlikely that such a requirement would make it into an Internet Standard.

To understand the difference, let's take a look at what the SPF standard (RFC 7208) has to say on the topic:

   Starting with the set of records that were returned by the lookup,
   discard records that do not begin with a version section of exactly
   "v=spf1".  Note that the version section is terminated by either an
   SP character or the end of the record.  As an example, a record with
   a version section of "v=spf10" does not match and is discarded.

   If the resultant record set includes no records, check_host()
   produces the "none" result.  If the resultant record set includes
   more than one record, check_host() produces the "permerror" result.

In short, TXT records which do not meet the syntax requirements of SPF are ignored. An error only occurs in the case where multiple records match SPF syntax.

(DMARC syntax carries the same restriction, for those who might be wondering.)

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If you are using Google Domains, when you edit the TXT record, there's a plus(+) symbol next to the TXT value... click that to add multiple values.

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