Timeout in a connection to a DHCP server

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http://askubuntu.com – I want to configure my eth0 interface using an external DHCP server (resident in my subnet), so I edited /etc/network/configure with the lines auto eth0 iface eth0 inet dhcp but I also want to use avahi autoconfiguration when the DHCP server is down. So I tried ifup eth0 when the server is down, and after a certain amount of time it fails, but the interface eth0:avahi is correctly configured. What I'm looking for is a way to decrease the amount of time spent trying to connect to a DHCP server. And ... is this the right way to use avahi when there's no DHCP server? (HowTos)