Failover stability (peer holds all free leases)

David W. Hankins David_Hankins at
Wed Jul 5 16:20:48 UTC 2006

On Wed, Jul 05, 2006 at 10:55:28AM -0400, Keith Lawson wrote:
> - win2k pc gets a lease
> - manually release that lease
> - when I attempt to renew, primary server gets DHCPREQUEST and sends a
> DHCPACK. Then I see a DHCPDISCOVER message from the client that gets
> load balanced to the slave server. 
> - The slave server sees a DHCPREQUEST for an IP that the master holds so
> sends a DHCPNAK message.

What version is this?

The above doesn't describe any ISC DHCP failover behaviour I'm aware

If the lease is owned by the primary, it will simply fail to
won't NAK on that basis.  All you should get is "lease owned by peer"

> Shouldn't the client accept the first DHCPACK and never send the
> DISCOVER message? 

The client shouldn't send a DHCPREQUEST if it has DHCPRELEASEd its

The DHCPDISCOVER should be the first message it transmits.

David W. Hankins		"If you don't do it right the first time,
Software Engineer			you'll just have to do it again."
Internet Systems Consortium, Inc.		-- Jack T. Hankins

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