Web Server Administration and PHP Development

krsort() sorts an associative array by key in reverse order (descending) while maintaining key-value associations. ksort() sorts ascending by keys. asort() sorts ascending by values. usort() sorts by values using a custom comparison function and doesn't maintain key associations.

mysql_query() executes a SQL query on the MySQL server and returns a result resource. mysql_fetch_array() fetches a row from the result set as an array. Options A and B are fictional functions that don't exist in PHP's MySQL extension.

pg_numrows() is the PostgreSQL function to get the number of rows in a result set. mysql_num_rows() is the MySQL equivalent. Options B and D are incorrect function names - postregSQL_numRows has a typo and ora_num_rows is not the correct Oracle function name.

The statement is backwards - require() raises a fatal error (stops execution) if the file is not found, while include() only raises a warning and continues execution. This is a fundamental difference in how PHP handles missing files between these two constructs.

The Data Replication Service (DRS) in WebSphere defaults to single replica configuration, which provides basic data redundancy without the overhead of replicating to multiple servers.

The Maximum in-memory session count property controls how many active sessions the Web container maintains in memory. Sessions beyond this limit may be passivated to disk or secondary storage.

The Upstream Queuing model recommends graduated capacity: web server handles most connections (75), intermediate layers fewer (50 for web container), and backend resources least (25 for datasources). This prevents overwhelming downstream resources.

The dumpNameSpace utility is primarily used for diagnosing JNDI and namespace-related issues, including applications having trouble accessing specific WebSphere resources like data sources that are registered in the JNDI namespace.

Multi-tiered environments distribute components across machines based on function. This separation allows OS tuning parameters to be optimized for each machine's specific role (e.g., web server vs. application server vs. database).

Once a managed server is configured and synchronized with the deployment manager, it can start independently. The node agent must be running (it manages the server process), but the deployment manager itself is not required for startup.

Low database connection pool utilization despite high activity suggests an upstream bottleneck. If earlier processing stages are slow, requests never reach the database layer efficiently, resulting in underutilized database connections.

The GenPluginCfg command must be run on the deployment manager to generate a cell-wide plugin configuration. The deployment manager has the complete view of all applications and servers in the cell.

Virtual host configuration isolates web modules by controlling which applications/resources can be accessed through specific virtual hosts. This provides security and resource separation between different web modules.

This is a duplicate of question 142149. Low database connection pool utilization during active application usage indicates an upstream bottleneck: earlier processing stages are constraining flow before database requests can be made.