This optional parameter can be used to specify a default realm
to use for requests that have a User-Name that does not include a realm.
The realm can then be used to trigger a specific <Realm> or
<Handler> clause. This is useful if you operate a number of NASs for
different customer groups and where some or all of your customers log in
without specifying a realm.
# Realmless logins to this NAS will be treated
# as if they are for realm open.com.au
<Client acc1.open.com.au>
Secret ....
DefaultRealm open.com.au
</Client>
<Realm open.com.au>
.....
</Realm>
Tip
Under some circumstances, some NASs
send requests with no User-Name (usually for administrative reports). In
that case, DefaultRealm will not add a realm to the User-Name, nor create
a User-Name.