Computer Networks

Tutorial #6

1. In the lecture, the statement was made that the various versions of HTTP are backwards compatible. What does this mean?

2. In HTTP/1.0 the GET request (and other types as well, but we didn't elaborate in the lecture) is terminated by two newlines. Why are two necessary? Wouldn't one newline be sufficient, as in HTTP 0.9?

3. The method response from a HTTP/1.0 server is a MIME compatible document.
   1. What does this mean?
   2. What is the MIME type for ordinary Web pages in HTTP/1.0?
   3. Why is the "Content-length: " header required in HTTP/1.0?
   4. Why isn't an SMTP MIME "Content-encoding: " header required in HTTP/1.0 as it is for email?

4. A browser makes the following request to a Web server:

   GET /Fig1.gif HTTP/1.0<newline><newline>
   

   What would the server return? Explain in some detail.

5. What is the HTTP/1.0 HEAD request method used for?

6. A client can optionally include a GET request method header of the form If-Modified-Since:
   1. Why is this used?
   2. Why is the date/time specified in GMT (UTC) instead of local time?
   3. This header takes a date/time value. Is there an Internet standard format for this value? Hint: look at section 3.3 of RFC1945

7. The HTTP/1.0 specification permits a GET request method to include a "Referer: " header in the request. Why is this considered to be a potential privacy issue?

8. (Tricky question) In HTTP/0.9, there was no way to specify the content type in objects returned from the server. How did the browser know whether it was receiving a Web page (in HTML), a GIF image, a sound sample or whatever?

9. Give some of the reasons why HTTP/1.0 is not a highly regarded protocol in the Internet technical community. How does HTTP/1.1 address these problems? At least two points required.

10. Contemplate this: the specification for the original version of HTTP (0.9) was approximately 6 Kbytes in size. The RFC for HTTP/1.0 (RFC1945) was 134 Kbytes. The RFC for the current version of HTTP/1.1 (RFC2068) is 369 Kbytes. What conclusions can you draw?