After rebooting the host, you attempt to start the mysqld service. You get the following error: Can't start server: Bind on TCP/IP port: Address already in use What is the most likely cause of this…

Question

Options

• AThe mysql service has already been started on the same port.
• BThe network service process in the server is frozen, so all TCP/IP connections are paused and cannot be reused.
• CYou failed to specify the port number 3306 to the command to start the server, so it is defaulting to port 80, which is in use by the built-in web server.
• DThe /etc/hosts file does not have a valid IP entry for mysqld localhost, so it is binding to 127.0.0.1, which is already in use.
• EThe mysql.sock file in the MySQL /tmp directory was not removed after the reboot, so mysqld still thinks there is an active server running.

• A
  2% (1)
• B
  7% (3)
• C
  9% (4)
• D
  2% (1)
• E
  79% (34)

Explanation

Option E is correct because when a MySQL server crashes or is improperly shut down before a reboot, the mysql.sock Unix socket file in /tmp (or /var/lib/mysql/) can persist. When mysqld starts and finds this leftover socket file, it may interpret it as evidence of a running instance and fail to properly initialize, which can manifest as a TCP/IP binding error during startup. The fix is to manually delete the stale mysql.sock file and then restart the service.

Why the distractors are wrong:

• A is plausible-sounding but wrong - a fresh reboot clears all running processes, so a duplicate MySQL instance is extremely unlikely unless it auto-started during boot and you then tried to start it again manually.
• B is fabricated - there is no concept of a "frozen network service process" that pauses TCP/IP reuse at the OS level like this.
• C is wrong - MySQL defaults to port 3306, not port 80, and you don't need to manually specify the port to start the server.
• D is wrong - /etc/hosts entries affect hostname resolution, not TCP socket binding conflicts; 127.0.0.1 being "in use" generically is not a valid failure mode.

Memory tip: Think of the .sock file as a "ghost" - MySQL sees it after a reboot and believes another server is haunting the port. When MySQL crashes, always clean up the ghost (rm /tmp/mysql.sock) before restarting.

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