1. Application layer

2. OSI model

Application layer

3. Actually covers

Application

4. Presentation 5. Session 6. Application achitechture Peer-to-peer Client/server 7. Application layer protocols

To be discussed

HTTP

8. SMTP 9. DNS Other examples

HTTPS

10. Streaming 11. FTP 12. HTTP

You know this one

Client/Server or P2P?

13. TCP or UDP? A standard

RFC 1945 and 2616

14. HTTP questions

What is the relationship between HTTP and HTML?

15. What is GET and POST? 16. Default port number for HTTP? 17. HTTP response message Other possibilities:

404 not found

18. 400 Bad request 19. 301 Moved permanently 20. And more. See RFCs for details. 21. Exercise

Telnet or hyperterminal to a HTTP server

Ex. www.sde.dk

GET / HTTP/1.1

22. host:www.sde.dk 23. Why HTTP stuff? 24. Why host? 25. Possible solution Send Received 26. Web proxy

Caches data

Reduces bandwidth usage, increases responsiveness

27. Uses If-modified-since header line 28. Homework

Install wireshark

29. Redo the HTTP exercise, both using a browser and telnet.

What do you see in wireshark?

30. SMTP example

Connect and send an email using telnet.

31. DNS 32. DNS root servers Root server geographically 33. Dns exercise

dig dr.dk

34. dig dr.dk MX 35. dig google.com 36. dig @dns101.telia.com google.com 37. And how does this look in wireshark?