1. User Datagram Protocol (UDP)

2. UDP Connectionless services Some apps
No reliability checks (sequencing/acks)
Some apps
Network monitoring
DNS name resolution
Streaming audio & video

3. Frame format
Source Port/Destination Port: A port (socket/session) Virtual circuit between two communicating processes on two different computers or devices
The source port is the port on the sending device.
The destination port is a TCP port on a receiving device that corresponds with the source port on the sending device
Length: contains information about the length of the frame
Checksum: The checksum is a 16-bit cyclic redundancy check (CRC) that is computed by adding the length of all header fields plus the length of the data payload field (the sum of all fields in the TCP segment).
Placed in the frame by the sending station.
The recipient also calculates the checksum and compares its calculation with the value in the checksum field.