The state of this trusted host entry. Enable (1) defines an
entry that is valid. Disable (2) defines an entry that is
valid but not enabled. Delete (3) removes an entry from the
table. Invalid (4) defines an entry that is no longer valid
(e.g., an entry that was deleted) and should be ignored. An
attempt to set a value of invalid (4) causes the agent to
return SNMP_BADVALUE.