Which of the following tools are used to measure network I/O?

`iostat` is primarily used to monitor system input/output device load for local disks and storage, not network I/O.

The `netstat` (network statistics) command-line utility provides comprehensive information about network connections, routing tables, and network interface statistics, which includes data related to network input/output such as packets and bytes transmitted and received.

`route` is a command used to view or manipulate the IP routing table, not to measure network I/O performance.

`vmstat` reports virtual memory statistics, as well as CPU, disk, and trap activity, but does not focus on network I/O.