ODL won't boot correctly if dead DNS server is present.

1. cat /etc/resolv.conf
2. Using IPTABLES cut each IP address reported in step 1 so that
traffic sent to them is silently dropped.
3. /where/your/odl/is/located/bin/start

These "step 2" actions could also work but they were not tested:

• Cut only one DNS IP address, make the rest inaccessible (connection
  refused or so on).
• Configure a DNS server that takes 2 minutes to provide any data.

The symptoms are that the ODL takes significantly longer to boot and the karaf console becomes inacessible (attempt to connect to the karaf console will result in opened connection whose other end does not respond to anything).