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RLBChrisBriant
Asked: 2021-02-02 12:13:17 +0800 CST

Is it safe to add additional values to a TXT record in DNS

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In Dynamics 365 we need to be able to authenticate our domain for sending marketing emails. We have followed the advice in the Microsoft article below and now need to add the DNS records.

https://docs.microsoft.com/en-gb/dynamics365/marketing/mkt-settings-authenticate-domains#:~:text=all%20new%20instances.-,Authenticate%20a%20domain,of%20existing%20authenticated%20domains%20opens.

The TXT record it gives in the configuration is for the top level domain of our organisation. That is the one we want to authenticate. The thing is that our DNS already has a TXT record with the '@' symbol. I understand that this is a shortcut to the top level domain. If I were to add the additional value to that existing record of the key given in Dynamics 365, will that cause any issues? Is it safe to do that?

The text record already has values for SPF and some other keys.

domain-name-system txt-record

2 Answers

  1. Most of the semi-common things that store values in TXT records at the root are smart enough to have some kind of identifier in the record, or just accept all the TXT records and just look through them for the value they want.

    Common TXT types that with some identifiers. SPF TXT record will start with v=spf1. DMARC with v=DMARC1; Google site verifications will start with google-site-verification=.

    From your link

    TXT value: d365mktkey=abc123abc123abc123abc123

    The d365mktkey= part is used to define this record is for dynamics.

    Anyway, nothing should break by adding another TXT record.

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  2. Best Answer

    It's safe to have multiple values in a single TXT record.

    Route53 (AWS DNS service) for example will not allow multiple TXT records for a specific value in a zone. Other DNS providers will allow you to break them out, but if you dig for TXT records you'll get all of them back anyway so there really isn't a reason to break them up.

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