When the network mask is 255.255.255.224 what is the highest  total usable host?
CREATE TABLE table_149426_4 (total_usable_hosts INTEGER, network_mask VARCHAR)
SELECT MAX(total_usable_hosts) FROM table_149426_4 WHERE network_mask = "255.255.255.224"
<s>[INST] Write mssql query to answer the following question given the database schema. Schema: CREATE TABLE table_149426_4 (total_usable_hosts INTEGER, network_mask VARCHAR) Question: When the network mask is 255.255.255.224 what is the highest  total usable host? [/INST] SELECT MAX(total_usable_hosts) FROM table_149426_4 WHERE network_mask = "255.255.255.224" </s>