how to set up wildcard dns

one address fits all:

/etc/bind/wildcard.conf:

zone "." {
        type master;
        file "/etc/bind/wildcard.zone";
};

/etc/bind/wildcard.zone:

$TTL    604800
@       IN      SOA     .       root.localhost. (
                1       ; serial
        604800  ; refresh
        86400   ; retry
        2419200 ; expire
        604800  ; negative cache ttl
)
        IN      NS      10.1.2.31
*.      IN      A       10.1.2.31