Knowledge checks


“HTTP is stateless.” 



What do we mean when we say “HTTP is stateless”? In answering this question, assume that cookies are not used.  Check all answers that apply.




 

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1/15

HTTP cookies. 



What is an HTTP cookie used for?




 

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2/15

The HTTP GET.



  What is the purpose of the HTTP GET message?




 

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3/15

Conditional HTTP GET. 



What is the purpose of the conditional HTTP GET request message?




 

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4/15

A detailed look at an HTTP GET (1).



Suppose a client is sending an HTTP GET request message to a web server, gaia.cs.umass.edu. Suppose the client-to-server HTTP GET message is the following:

GET /kurose_ross_sandbox/interactive/quotation2.htm HTTP/1.1
Host: gaia.cs.umass.edu
Accept: text/plain, text/html, text/xml, image/jpeg, image/gif, audio/mpeg, audio/mp4, video/wmv, video/mp4,
Accept-Language: en-us, en-gb;q=0.1, en;q=0.7, fr, fr-ch, da, de, fi
If-Modified-Since: Wed, 09 Sep 2020 16:06:01 -0700
User Agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/535.11 (KHTML, like Gecko) Chrome/17.0.963.56 Safari/535.11

What version of HTTP is the client using?

[Note: you can find additional questions similar to this here.]




 

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5/15

A detailed look at an HTTP GET (2).



Again, suppose a client is sending an HTTP GET request message to a web server, gaia.cs.umass.edu.  The client-to-server HTTP GET message is the following (same as in previous problem):


GET /kurose_ross_sandbox/interactive/quotation2.htm HTTP/1.1
Host: gaia.cs.umass.edu
Accept: text/plain, text/html, text/xml, image/jpeg, image/gif, audio/mpeg, audio/mp4, video/wmv, video/mp4,
Accept-Language: en-us, en-gb;q=0.1, en;q=0.7, fr, fr-ch, da, de, fi
If-Modified-Since: Wed, 09 Sep 2020 16:06:01 -0700
User Agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/535.11 (KHTML, like Gecko) Chrome/17.0.963.56 Safari/535.11

What is the language in which the client would least prefer to get a response?  [You may have to search around the Web a bit to answer this.]

[Note: you can find additional questions similar to this here.]




 

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6/15

A detailed Look at an HTTP GET (3).



Again, suppose a client is sending an HTTP GET request message to a web server, gaia.cs.umass.edu. Suppose the client-to-server HTTP GET message is the following (same as in previous problem):


GET /kurose_ross_sandbox/interactive/quotation2.htm HTTP/1.1
Host: gaia.cs.umass.edu
Accept: text/plain, text/html, text/xml, image/jpeg, image/gif, audio/mpeg, audio/mp4, video/wmv, video/mp4,
Accept-Language: en-us, en-gb;q=0.1, en;q=0.7, fr, fr-ch, da, de, fi
If-Modified-Since: Wed, 09 Sep 2020 16:06:01 -0700
User Agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/535.11 (KHTML, like Gecko) Chrome/17.0.963.56 Safari/535.11

Does the client have a cached copy of the object being requested?

[Note: you can find additional questions similar to this here.]





 

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7/15

A detailed look at an HTTP reply.



Suppose now the server sends the following HTTP response message the client:

HTTP/1.0 200 OK
Date: Wed, 09 Sep 2020 23:46:21 +0000
Server: Apache/2.2.3 (CentOS)
Last-Modified: Wed, 09 Sep 2020 23:51:41 +0000
ETag:17dc6-a5c-bf716880.
Content-Length: 418
Connection: Close
Content-type: image/html

Will the web server close the TCP connection after sending this message?

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




 

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8/15

Why Web Caching?



Which of the following are advantages of using a web cache? Sselect one or more answers.




 

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9/15

HTTP/2 versus HTTP/1.1.



  Which of the following are changes between HTTP 1.1 and HTTP/2? Note: select one or more answers.




 

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10/15

What's in an HTTP reply?



Which of the following pieces of information will appear in a server’s application-level HTTP reply message? (Check all that apply.)




 

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11/15

If-Modified-Since.



What is the purpose of the If-Modified-Since field in a HTTP GET request message




 

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12/15

Cookies.



What is the purpose of a cookie value in the HTTP GET request?




 

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13/15

HTTP GET (even more).



Suppose a client is sending an HTTP GET message to a web server, gaia.cs.umass.edu. Suppose the client-to-server HTTP GET message is the following:


GET /kurose_ross_sandbox/interactive/quotation2.htm HTTP/1.1
Host: gaia.cs.umass.edu
Accept: text/plain, text/html, text/xml, image/jpeg, image/gif, audio/mpeg, audio/mp4, video/wmv, video/mp4,
Accept-Language: en-us, en-gb;q=0.1, en;q=0.7, fr, fr-ch, da, de, fi
If-Modified-Since: Wed, 09 Sep 2020 16:06:01 -0700
User Agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/535.11 (KHTML, like Gecko) Chrome/17.0.963.56 Safari/535.11

Does the client have a cached copy of the object being requested?




 

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14/15

What happens after an HTTP reply?



Suppose an HTTP server sends the following HTTP response message a client:

HTTP/1.0 200 OK
Date: Wed, 09 Sep 2020 23:46:21 +0000
Server: Apache/2.2.3 (CentOS)
Last-Modified: Wed, 09 Sep 2020 23:51:41 +0000
ETag:17dc6-a5c-bf716880.
Content-Length: 418
Connection: Close
Content-type: image/html

Will the web server close the TCP connection after sending this message?




 

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15/15

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

Copyright © 2010-2021 J.F. Kurose, K.W. Ross
Comments welcome and appreciated: kurose@cs.umass.edu