Why does Debian squeeze forget its static IP address and seek a DHCP lease?

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http://serverfault.com – Hi have a Debian Squeeze box with eth0 and eth1. In /etc/network/interfaces is: auto eth1 iface eth1 inet static address netmask gateway But every 24 hours, eth1 loses its statically-assigned IP address, and fetches one from DHCP instead! Manually doing: # ifup eth1 && ifdown eth1 puts it back to how it should be. But why does it spontaneously break in the first place?! (HowTos)