The ____________ command is used to send ICMP ECHO_REQUEST packets to other hosts over the network

Answer: ping

Explanation:
From the man pages:
ping uses the ICMP protocol’s mandatory ECHO_REQUEST datagram to elicit an ICMP ECHO_RESPONSE from a host or gateway. ECHO_REQUEST datagrams (“pings”) have an IP and ICMP header, followed by a struct timeval and then an arbitrary number of “pad” bytes used to fill out the packet.