Multiple SOA records?

Kevin Darcy kcd at
Wed May 7 22:32:33 UTC 2008

Lars Hecking wrote:
> Kevin Darcy writes:
> [...]   
>> definitely seems to have a standards-conformance issue 
>> in the way it handles SOA queries
> [...]
>  Hhm, I think I would disagree here. After all, their name servers do return
>  SOA records when queried directly, even if they are too many.
Semantics. There can only be one SOA RR in a given zone. SOA RRs must 
have an owner name which is identical to the zone name. Put those two 
things together, and you get that a given name can only own at most one 
SOA RR. Expressed another way, SOA is a "singleton type".

Are you with me so far?

These servers are responding, to a regular query (as opposed to a 
zone-transfer request) with two SOA RRs that have the same owner name 
but different RDATA. How can this possibly conform to standards? One of 
those RRs -- take your pick -- can't be legally owned by its owner name, 
because of the existence of the other RR. One of them conforms to 
standards; the other one violates them.

                           - Kevin

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