failover - reserved address

Simon Hobson dhcp1 at
Mon May 18 14:13:39 UTC 2009

Pavel Mlãoch wrote:

>I don't know if I understand right. When I mark 
>leases by adding line "reserved;" is the same as 

No, they are VERY different features/functions.

A host statement with fixed address is very 
different to a normal dynamic lease. Although 
from the client side it looks the same, at the 
server end there is no lease processing, no 
dynamic DNS updates, etc - in fact a lease will 
never appear in the leases file for these 
clients. Failover is not involved at all, and you 
should just define the same host statement on 
each server.

A lease marked as reserved acts EXACTLY like a 
dynamic lease - it appears in the leases file, it 
expires, dynamic DNS updates happens, etc. The 
only difference is that once you add the reserved 
flag, the server will NOT reallocate that address 
to another client, even when it's expired. In a 
failover environment, I assume it goes through 
the same processing as any other lease.

>Isn't possible use omshell for this change on running server?

IIRC from previous discussion on here, no you can't.

Simon Hobson

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