The final tab is Access Lists, which enables you to allow or deny access to your network's DNS servers for specified blocks of network addresses (known as netblocks). This can be useful if you need to grant access to them for remote users (such as users connecting through a VPN), or to deny access to certain local netblocks. You can add an access list entry by clicking on the green +Add down button and to the right of the access list table.
The first option is the Access List name, in which you can specify a name for the access list. The next option is the Action drop-down box, in which you can specify what to do with DNS queries that originate on the netblock defined by this access list entry. The options are as follows:
