Knowledge checks


Does UDP preserve application-layer message boundaries?



True or False:  On the sending side, the UDP sender will take each application-layer chunk of data written into a UDP socket and send it in a distinct UDP datagram. And then on the receiving side, UDP will deliver a segment’s payload into the appropriate socket, preserving the application-defined message boundary.




 

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1/9



UDP header fields. Which of the fields below are in a UDP segment header? [Hint: note the use of the word "header" in this question statement.]




 

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2/9

UDP segment length field.



Why is the UDP header length field needed?




 

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3/9

Internet checksum and UDP.



Over what set of bytes is the checksum field in the UDP header computed over?




 

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4/9

Computing the Internet Checksum (1).



Compute the Internet checksum value for these two 16-bit words: 11110101 11010011 and 10110011 01000100

[Note: you can find more problems like this one here.]




 

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5/9

Computing the Internet Checksum (2).



Compute the Internet checksum value for these two 16-bit words: 01000001 11000100 and 00100000 00101011

[Note: you can find more problems like this one here.]




 

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6/9

UDP Checksum: how good is it?



True or False:  When computing the Internet checksum for two numbers, a single flipped bit (i.e., in just one of the two numbers) will always result in a changed checksum.




 

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7/9

UDP Checksum: how good is it?



True or False: When computing the Internet checksum for two numbers, a single flipped bit in each of the two numbers will always result in a changed checksum.




 

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8/9

IP addresses and port numbers in a UDP segment sent in reply. 



Suppose a UDP segment (A in the figure below) arrives at a host with an IP address of 128.119.40.186. The source port in the UDP segment is 4829 and the destination port is 3546. The IP address of the sending host is 60.54.75.24.


Now consider the UDP datagram (and the IP datagram that will encapsulate it) sent in reply by the application on host 128.119.40.186  to the original sender host, labeled B in the figure above.  Complete the sentences below ...

What are the source and destination port numbers and IP addresses? (Enter the integer port number or the 4-part dotted decimal IP address, included the period)

The source port number of the UDP segment (B) sent in reply is: 

The source IP address of the IP datagram containing the UDP segment (B) sent in reply is: 

The destination port number of the UDP segment (B) sent in reply  is:

The destination IP address of the IP datagram containing the UDP segment (B) sent in reply is: 

[Note: you can find more problems like this one here.]



Question List:
Answer List:
  1. 4829
  2. 3546
  3. 128.119.40.186
  4. 60.54.75.24

 

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9/9

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