Question

What is a datagram ?

Answer 1

pls.......

Answer 2

A datagram is the PDU of UDP, it's how what it constructs to send over the network to communicate, it's not reliable and considered connection-less. It's more light-weight than a packet (TCP's way of communicating).

When a datagram fragments, it fragments into packets (though not to be confused with TCP packets)
When a packet is fragmented, it fragments into segments (to assert that they're still reliable).

In short, a datagram is how UDP communicates, and this is it's structure:
http://mars.netanya.ac.il/~unesco/cdrom/booklet/HTML/NETWORKING/node020.html

Answer 3

thanks...