Do you know how to set up DNS name configuration in the next files:

  •  /etc/resolv.conf is wrong then your firewall won't start.

  • If your /etc/nsswitch.conf is wrong then your firewall won't start.

  • If your Name Server(s) is(are) down then your firewall won't start.

  • If your startup scripts try to start your firewall before starting your DNS server then your firewall won't start.

  • Factors totally outside your control (your ISP's router is down for example), can prevent your firewall from starting.

  • You must bring up your network interfaces prior to starting your firewall.

Each DNS name must be fully qualified and include a minimum of two periods (although one may be trailing). This restriction is imposed by Shorewall to insure backward compatibility with existing configuration files. 

Those are just warnings about what may go wrong when you use DNS names.

-Tom