What is the maximum size of a UDP user datagram?20 bytes40 bytes60 bytesVaries depending on the options included

Understanding UDP Datagram Size

1. Break Down the Problem
   We need to determine the maximum size of a User Datagram Protocol (UDP) user datagram, which is influenced by various factors including protocol headers and payload limitations.

2. Relevant Concepts

   • UDP consists of a header and the data payload.
   • The total size of a UDP datagram (UDP header + payload) is determined by the maximum size of an IP datagram and the size of the UDP header.

3. Analysis and Detail

   • The standard maximum transmission unit (MTU) for Ethernet is 1500 bytes.
   • IP headers typically occupy 20 bytes and UDP headers typically occupy 8 bytes.
   • This leads to a maximum UDP payload size of:
     $\text{Maximum UDP Payload} = \text{MTU} - \text{IP Header Size} - \text{UDP Header Size} = 1500 - 20 - 8 = 1472 \text{ bytes}$
   • Therefore, the maximum size of a UDP user datagram varies depending on the options and headers included.

4. Verify and Summarize
   UDP datagram sizes can indeed vary based on the options and headers present. The maximum size can be as large as 1472 bytes given the standard MTU for Ethernet. However, the question options suggest a more restrictive interpretation.

Final Answer

The maximum size of a UDP user datagram varies depending on the options included; hence, the correct choice is: Varies depending on the options included.