Which php.ini setting is usually required to use an opcode cache?

Question

Options

• Aextension
• Bzend_extension
• Coptimizer
• Ddl

• A
  7% (2)
• B
  70% (21)
• C
  20% (6)
• D
  3% (1)

Explanation

zend_extension is required because opcode caches (like OPcache) operate at the Zend engine level - they intercept and cache compiled bytecode before PHP's normal execution flow. This deep engine integration requires zend_extension rather than the standard extension loader, so in php.ini you'd write zend_extension=opcache.so (Linux) or zend_extension=php_opcache.dll (Windows).

Why the others are wrong:

• A. extension loads ordinary PHP userland extensions (e.g., curl, pdo). These run on top of the Zend engine, not inside it - too shallow for an opcode cache.
• C. optimizer is not a valid php.ini directive; it's often confused with legacy products like "Zend Optimizer," but it doesn't load anything.
• D. dl is a PHP runtime function, not a php.ini setting, and it's deprecated - it was never the right tool for opcode caches.

Memory tip: Associate the Z in Zend_extension with Zero - opcode caches work at ground zero (the engine core), so they need the Zend-level hook. If it touches the engine itself, reach for zend_extension.

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