An ESXi 5.x host is unable to connect to a vCenter 5.x server. Which commands should an administrator use to restart the management agents on the host?

The hostd daemon is the ESXi Host Agent responsible for managing local host operations and exposing the API consumed by vCenter, while vpxa is the vCenter Agent that runs on the ESXi host and maintains the communication channel to vCenter Server. Restarting both services via /etc/init.d/hostd restart and /etc/init.d/vpxa restart refreshes the management plane without requiring a full host reboot.

vpxd is the vCenter Server daemon that runs on the vCenter Server itself, not on ESXi hosts; this command does not exist on an ESXi host and would not resolve host-side connectivity issues.

vmware-hostd is not the correct init.d service script name used in ESXi 5.x; the proper service name is simply hostd, making this command fail.

vpxd runs on the vCenter Server appliance or Windows host, not on ESXi nodes, so issuing this command from an ESXi SSH session is invalid and would not fix the agent connectivity problem.