RTT: how it works

[jefferson.f.moreira at hsbc.com.br]

Hi all.

I have a doubt on DNS servers behavior regarding RTT.

Consider the following diagram:


      cwb.somenet.net.br                  cwb.somenet.net.br
            [cs1]                                [cs2]
              |                                    |
              |                                    |
     +------[Sw1]------+                  +------[Sw2]-----+
     /      /   \       \                /       /   \      \
    /      /     \       \              /       /     \      \
 (NS1)  [Srv1]   [Srv2]   \            /    [Srv3]   [Srv4]  (NS2)
                           \          /
                        (Router)---(Router)
                             \      /
                              \    /
                             (Router)
                                |
[ Corp NS ]---------------------+


CS1/2 =3D Content Service Switches with DNS service
Sw1 =3D Switches
NS1/2 =3D Two Win2k Name servers. They=B4re not primary and secondary,
but two servers with the same db.

These questions apply to a query from an external NS (let=B4s say, a
corporate NS)querying NS1 that will delegate it to CS1.

q1: (this applies to the CSSs)
When there are 2 name servers (SOAs) for one domain, how is calculated
the Round Trip Time? At exactly what moment will be calculated this RTT
and how often?

q2: in the event of one of the CSx failing, will we have that 75s time
out? How to overcome that? What is the default behavior?

Thanks...
Jefferson.



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