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What is the purpose of the TXT record in (for example) the root zone? I don't see any reasonable tie into SPF, SenderID, DomainKeys, or even TLS-OBC or DANE for TLS. IN TXT FbUF6DbkE+Aw1/wi9xgDi8KVrIIZus5v8L6tbIQZkGrQ/rVQKJi8CjQbBtWtE64ey4NJJwj5J65PIggVYNabdQ==

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closed as too localized by Dan, RobM, Tom O'Connor, Greg Askew, EEAA Jun 18 '12 at 19:24

This question is unlikely to help any future visitors; it is only relevant to a small geographic area, a specific moment in time, or an extraordinarily narrow situation that is not generally applicable to the worldwide audience of the internet. For help making this question more broadly applicable, visit the help center.If this question can be reworded to fit the rules in the help center, please edit the question.

Seeig as it is there dns record, they could use that for anything they please, huh? – uSlackr Jun 18 '12 at 1:27
@uSlackr True, but I doubt they would run experiments on a production domain like that. There has to be a public RFC out there somewhere, because doing things like this may break other experimental RFCs. – LamonteCristo Jun 18 '12 at 1:52
@makerofthings7 Why would a TXT record break anything? It's a base-64 encode of a 64 byte chunk of.. something. A SHA512 hash of something is my best guess. – Shane Madden Jun 18 '12 at 2:05
They also have a standard SPF record along side of the base64-encoded string, so not breaking anything. Decoding the encoded record doesn't really give me anything meaningful, just some binary data that they could be using for any number of purposes. – Justin Scott Jun 18 '12 at 2:17
In regards to the "Too localized" reason, it seems this is related to a new, broadly available feature that is available to any Exchange customer. We will be seeing much more of these in the future, so I voted to reopen. – LamonteCristo Jun 18 '12 at 20:41
up vote 5 down vote accepted

It looks like an Exchange federation "proof record". More information here:

MS documentation:

Anyway, we can use TXT records for anything, or at least that's what I understand reading "The semantics of the text depends on the domain where it is found." (RFC 1035)

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I tried running the command Get-FederationInformation for and it failed then genereated a Watson. Exchange 2010 SP1 RU6, and SP2 RU2 – LamonteCristo Jun 18 '12 at 14:11

In fact, there are several TXT records. If you run dig TXT:

;; ANSWER SECTION:      3600    IN  TXT "FbUF6DbkE+Aw1/wi9xgDi8KVrIIZus5v8L6tbIQZkGrQ/rVQKJi8CjQbBtWtE64ey4NJJwj5J65PIggVYNabdQ=="      3600    IN  TXT "v=spf1 ip4: ip4: ip4: ip4: ip4: ~all"

So there is standart SPF record available while an additional header that may have custom purpose e.g. anything the developers/domain managers wanted.

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