I would use "space-separated".

To avoid the introductory word with an immediate pause:

A simpler way to express this is with a space-separated list of ranges:

You only want 1 addresses in each subnet to have the real subnet mask. As the example shows, you can have addresses in 2 or more subnets, as separate ranges. So if you're in 202.0.75.16/28, and 202.0.75.32/28, you'd do: inet 202.0.75.17-29/28 inet 202.0.75.33-61/28 or similar.

You could do 202.0.75.17-61/28 or something, and all of the extra addresses would be /32s. However, you wouldn't be able to reach other hosts in the 2nd subnet directly, since you have no route in that subnet.

However, I think this is beyond the scope of the handbook.

The blank line between the </programlisting> and </sect1> should be removed. Unless it was in the original, phabricator is making it hard to tell.