UDP datagram structure in Computer Networks - Practice Problems & Coding Challenges

Challenge - 5 Problems

📋 Factual

intermediate

Identify the UDP header field size

Which of the following fields in a UDP datagram header is 16 bits (2 bytes) in size?

A All of the above

B Source Port

C Checksum

D Length

💡 Hint

Think about the size of each field in the UDP header.

All UDP header fields (Source Port, Destination Port, Length, and Checksum) are 16 bits (2 bytes) each.

🧠 Conceptual

intermediate

Purpose of the UDP Length field

What does the Length field in a UDP datagram header represent?

A The length of the data payload only

B The length of the UDP header only

C The length of the IP header

D The length of the UDP header plus data

💡 Hint

Consider what the UDP datagram consists of.

The Length field specifies the total length of the UDP header plus the data payload in bytes.

🔍 Analysis

advanced

Analyzing UDP checksum behavior

If the UDP checksum field is set to zero, what does this indicate?

A The checksum is not used and no error checking is performed

B The checksum is calculated but the value is zero

C The checksum field is corrupted

D The checksum is mandatory and zero is invalid

💡 Hint

Think about optional checksum usage in UDP.

In IPv4, a UDP checksum of zero means the checksum is disabled and no error checking is done. In IPv6, checksum is mandatory and cannot be zero.

❓ Comparison

advanced

Comparing UDP and TCP header sizes

Which statement correctly compares the header sizes of UDP and TCP?

A UDP header is fixed at 8 bytes; TCP header is fixed at 20 bytes

B UDP header is fixed at 8 bytes; TCP header size varies but minimum is 20 bytes

C UDP header size varies; TCP header is fixed at 8 bytes

D Both UDP and TCP headers have variable sizes starting at 8 bytes

💡 Hint

Consider the minimum and variable header sizes of TCP and UDP.

UDP header size is always 8 bytes. TCP header has a minimum size of 20 bytes but can be larger due to options.

❓ Reasoning

expert

Determining UDP payload size from header fields

Given a UDP datagram with a Length field value of 60 bytes, what is the size of the data payload?

A 68 bytes

B 60 bytes

C 52 bytes

D 8 bytes

💡 Hint

Remember the UDP header size when calculating payload size.

The UDP Length field includes the header (8 bytes) plus the data. So payload size = Length - 8.