Most of the people think that we use transport protocol for LAN communication but in fact LAN communication based...
on MAC address (a unique hardware address of each NIC) that can be viewed by "ipconifg/all" command. When ping command executes it searches ARP cache for destination address first. If found it uses else broadcast ICMP message. You can check your system ARP cache by "arp -a" command.
Dig Deeper on LANs (Local Area Networks)