Server System Variables Maximum Value 65536 The MySQL server maintains an in-memory host cache that contains client host name and IP address information and is used to avoid Domain Name System (DNS) lookups; see Section 5.1.12.3, “DNS Lookups and the Host Cache” . The  host_cache_size  variable controls the size of the host cache, as well as the size of the Performance Schema  host_cache  table that exposes the cache contents. Setting  host_cache_size has these effects: •Setting the size to 0 disables the host cache. With the cache disabled, the server performs a DNS lookup every time a client connects. •Changing the size at runtime causes an implicit host cache flushing operation that clears the host cache, truncates the  host_cache  table, and unblocks any blocked hosts. The default value is autosized to 128, plus 1 for a value of  max_connections  up to 500, plus 1 for every increment of 20 over 500 in the  max_connections  value, capped to a limit of 2000. Using the  --skip-host-cache  option is similar to setting the  host_cache_size  system variable to 0, but  host_cache_size  is more flexible because it can also be used to resize, enable, and disable the host cache at runtime, not just at server startup. Starting the server with  --skip-host-cache  does not prevent runtime changes to the value of  host_cache_size , but such changes have no effect and the cache is not re-enabled even if  host_cache_size  is set larger than 0. • hostname • identity System Variable hostname Scope Global Dynamic No SET_VAR  Hint Applies No Type String The server sets this variable to the server host name at startup. The maximum length is 255 characters as of MySQL 8.0.17, per RFC 1034, and 60 characters before that. This variable is a synonym for the  last_insert_id  variable. It exists for compatibility with other database systems. You can read its value with  SELECT @@identity , and set it using  SET identity . • init_connect Command-Line Format --init-connect=name System Variable init_connect Scope Global Dynamic Yes SET_VAR  Hint Applies No Type String A string to be executed by the server for each client that connects. The string consists of one or more SQL statements, separated by semicolon characters. 807