Interactive end-of-chapter exercises

Electronic Mail and SMTP

Look at the scenario below, where Alice sends an email to Bob.


For the questions below, assume both Bob's and Alice's user agents use the HTTP protocol.


Question List


1. At point 2 in the diagram, what protocol is being used?

2. At point 4 in the diagram, what protocol is being used?

3. At point 6 in the diagram, what protocol is being used?

4. Does SMTP use TCP or UDP?

5. Is SMTP a 'push' or 'pull' protocol?

6. Is HTTP a 'push' or 'pull' protocol?

7. What port does SMTP use?

8. What port does HTTP use?



Solution


1. At point 2 in the diagram, the SMTP protocol is used.

2. At point 4 in the diagram, the SMTP protocol is used.

3. At point 6 in the diagram, the HTTP protocol is used.

4. SMTP uses the TCP protocol.

5. SMTP is a 'push' protocol

6. HTTP is a 'pull' protocol

7. SMTP uses port 25

8. HTTP uses port 80


That's incorrect

That's correct

The answer was: SMTP

Question 1 of 8

The answer was: SMTP

Question 2 of 8

The answer was: HTTP

Question 3 of 8

The answer was: TCP

Question 4 of 8

The answer was: push

Question 5 of 8

The answer was: pull

Question 6 of 8

The answer was: 25

Question 7 of 8

The answer was: 80

Question 8 of 8

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We gratefully acknowledge the programming and problem design work of John Broderick (UMass '21), which has really helped to substantially improve this site.

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