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I was wondering what happens when "Auto state switchover interval" is less than "Maximum client lead time" in DHCP?
The question was raised after reading definitions of MCLT & ASSI:

Maximum Client Lead Time: This determines two three things: A) The lease time for a new client request if the server responsible for that client is down and the other answers the request and B) The amount of time one server will wait for a dead partner server before it takes control of the entire IP address block. C) (added 8/5/13) The amount of time one server that had been down must be available to the other before "Partner Down" status will automatically be changed to "Normal" status. (See comments for an example of this) The default of 1 hour is generally good but you may want to tweak depending on your setup.

Again, we have definition below for Auto Switch interval:

5.State Switchover Interval: **Selecting this enables either server to enter "Partner Down" state should communication be interrupted for the number of minutes specified after the option (default 60) resulting in the remaining server taking full responsibility for the scope(**s). If this is not selected, an admin must manually choose to put the server into partner down state.

So If I'm getting this right, when MCLT timer expires, the partner is responsible for the whole scope BUT it's not actually doing anything UNTIL the "Change to partner down" button is presses manually,
And If I enable this "Auto Switchover" feature, It's like the button is getting clicked automatically, only after this the partner starts to use the whole scope for assigning IP addresses.

Please correct me if I'm wrong. So what happens when "Auto state switchover interval" is less than "Maximum client lead time" in DHCP?
It would be so much appreciated if you include your own definitions of MCLT & ASSI in your responses.
All the best!

"Definitions I used across the topic"
"TechNet-DHCP Failover Settings"

Sam
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  • Mike Brown, MCT tried to explain it [over at WindowsITPro](http://windowsitpro.com/windows-server-2012/dhcp-failover-windows-server-2012). – StackzOfZtuff Sep 18 '15 at 13:31

1 Answers1

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The partner server will become in partner down state as soon as the primary server is unreachable. From then on, the partner server will provide new leases from the stand-by scope. Once the state over interval is reached, it will take ownership of the complete scope. If the primary server comes back on-line, it not automatically resume the ownership of the scope. First the MCLT has to expire, before both servers return to normal operational mode.

Killerbe
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