dns server and client load blancing behavior

[Kevin Darcy]

®}®¶©[ wrote:

> 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?

Order of RRs within an RRset is undefined by the RFCs. In BIND, you can control
the order of RRs in an RRset using the "rrset-order" option (imagine that), but
your careful ordering may get mucked up by a server not under your control
giving out answers from its cache in whatever order it feels like.

> How long do Mircrosoft client or any other client will cache the RR?

If they follow standards, they'll cache the RRs for as long as the TTL values
that are specified on them. Note that the TTLs for RRs in any given RRset must
all be the same.


- Kevin