Routing tables are not needed when the devices are on the same subnet. This is handled through address resolution protocol (ARP). Per the <a href=”http://www.tcpipguide.com/free/t_ARPAddressSpecificationandGeneralOperation.htm”>TCP/IP Guide</a>:
<i>ARP Address Specification and General Operation
An Address Resolution Protocol transaction begins when a source device on an IP network has an IP datagram to send. It must first decide whether the destination device is on the local network or a distant network. If the former, it will send directly to the destination; if the latter, it will send the datagram to one of the routers on the physical network for forwarding. Either way, it will determine the IP address of the device that needs to be the immediate destination of its IP datagram on the local network. After packaging the datagram it will pass it to its ARP software for address resolution.
Basic operation of ARP is a request/response pair of transmissions on the local network. The source (the one that needs to send the IP datagram) transmits a broadcast containing information about the destination (the intended recipient of the datagram). The destination then responds unicast back to the source, telling the source the hardware address of the destination. </i> Look at the link shown above for more information about ARP.
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