dns server and client load blancing behavior

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dear all,

if I has following RR
ms1    IN    MX    0    ms1_1
           IN    MX    0    ms1_2
ms1_1    IN    A    10.10.10.1
               IN    A    10.10.10.2
               IN    A    10.10.10.3
ms1_2    IN    A    10.10.10.4
               IN    A    10.10.10.5
               IN    A    10.10.10.6

then query mx Record for ms1,will name server response all the above RRs for
client,and the what the RR order?
How long do Mircrosoft client or any other client will cache the RR?

thank you for your help,
eric