Connectionless describes communication between two network endpoints where we can send a packet from one side to another. Connectionless means that no dedicated end-to-end connection before data sent. IP connectionless is theoretically comparable to sending a letter to someone without notifying the recipient in advance. all the same; the device at one side transmits the packet to the other; without ensuring the availability of the recipient and ready to receiving the data. If there are problems with the transmission, it may necessary to resend the data several times.
Connectionless data communications work on the principle where the initial exchange; of control information not required to set up an end-to-end connection before packets forwarded. IP also does not need additional fields in the header to keep up an established connection. This process reduces the overhead of IP. But, with no pre-established end-to-end connection; senders are unaware whether destination devices are present and functional when sending packets; nor are they aware of the destination receives the packet; or if they are able to access and read the packet.
The Internet Protocol (IP) and User Datagram Protocol are connectionless protocols. These protocols generally described as stateless because the endpoints have no protocol-defined, way to remember where they are in a “conversation” of message exchanges. The alternative to the connectionless is connection-oriented protocols, which described as stateful because they can keep track of a conversation.