Drupal - settings.php

// Memcached Server URL and other settings.
$settings['memcache']['servers'] = ['localhost:11211' => 'default'];
$settings['memcache']['bins'] = ['default' => 'default'];
$settings['memcache']['key_prefix'] = 'pk';
// Memcache cache backend related configs for all caches.
$settings['cache']['default'] = 'cache.backend.memcache';
// Or some specific cache tables.
$settings['cache']['bins']['render'] = 'cache.backend.memcache';
$settings['cache']['bins']['dynamic_page_cache'] = 'cache.backend.memcache';