[Dnsmasq-discuss] MAN Page Link Broken? and redundancy question

Carlos Carvalho carlos at fisica.ufpr.br
Sat Sep 5 03:12:35 BST 2009

richardvoigt at gmail.com (richardvoigt at gmail.com) wrote on 4 September 2009 20:21:
 >On Fri, Sep 4, 2009 at 7:04 PM, Carlos Carvalho<carlos at fisica.ufpr.br> wrote:
 >> richardvoigt at gmail.com (richardvoigt at gmail.com) wrote on 4 September 2009 15:23:
 >>  >You could split the address pool into two and configure half on each.
 >>  >Then during normal operations there will be a race to offer an
 >>  >address, the client will accept only one.  If one fails, the other
 >>  >will continue offering addresses.  If one runs out of addresses, the
 >>  >other continues to work fine.  The only problem would be if one fails
 >>  >and the other runs out of addresses.
 >> Perhaps you can configure the full pool in both, provided you don't
 >> use no-ping. This way each server will send a ping and if it gets an
 >> answer it won't offer that address, even if it's not in its list of
 >> leases because the client chose the other server.
 >I wouldn't rely on the ping feature, you're almost certain to end up
 >with address conflicts any time one client becomes temporarily
 >unreachable for any reason (such as rebooting, etc, etc).

Yes, that's why I said perhaps. Note however that this also happens
with a single server if it has to give an address not in the current
(known) leases to a different machine than it was allocated to before.
Servers usually do the ping test before the change but if the previous
machine is still using the address and doesn't answer the ping a
conflict will happen.

The admin has to decide which is better for his particular case. I
suspect your suggestion of splitting will be better in the majority of

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