If
you using a Domain List, you can optionally enable
Automatically
expand to include subdomains
to also include the subdomains
of a specified domain. For example, if your domain list includes
paloaltonetworks.com, all lower level components of the domain name
(e.g., *.paloaltonetworks.com) will also be included as part of the
list. Keep in mind, when this setting is enabled, each domain in
a given list requires an additional entry, effectively doubling
the number of entries that are consumed.