DNS over TCP: Order of responses

When communicating over a TCP connection, are DNS servers expected to send 
responses in the same order as it received the corresponding queries, or is 
something like the following allowed?

      Resolver                                Nameserver
      --------                                ----------
      QR=0, ID=1000 example.com IN A ---->
      QR=0, ID=1234 heaven.af.mil IN A ---->
           <---- QR=1, ID=1234 heaven.af.mil IN A 10.0.0.1
           <---- QR=1, ID=1000 example.com IN A 10.0.0.2

I'm writing a small DNS server that forwards queries to other servers based 
on the contents of the query (QNAME, RD, etc.) so I need to know how both 
the resolver side and the nameserver side _should_ behave, as well as what 
I can expect from other software.

I didn't find anything in either RFC 1035 or RFC 2181 about this.  Any 
insights would be much appreciated.

Thanks,
   - Dwayne

-- 
Dwayne C. Litzenberger <[email protected]>
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