Wireshark Lab 2, Part 4: HTML Objects with Embedded Documents

Lab Video:

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STEPS:

Step 1: Start up your web browser, and make sure your browser’s cache is cleared, as discussed above.

Step 2:Start up the Wireshark packet sniffer

Step 3:Enter the following URL into your browser http://gaia.cs.umass.edu/wireshark-labs/HTTP-wireshark-file4.html Your browser should display a short HTML file with two images. These two images are referenced in the base HTML file. That is, the images themselves are not contained in the HTML; instead the URLs for the images are contained in the downloaded HTML file. As discussed in the textbook, your browser will have to retrieve these logos from the indicated web sites. Our publisher’s logo is retrieved from the http://www.aw-bc.com web site. The image of the cover for our 5th edition (one of our favorite covers) is stored at the manic.cs.umass.edu server.

Step 4: Stop Wireshark packet capture, and enter “http” in the display-filter-specification window, so that only captured HTTP messages will be displayed.

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QUESTIONS:

16. How many HTTP GET request messages did your browser send? To which Internet addresses were these GET requests sent?

• My browser sent 3 http GET message requests. One each to each for each of the following: The initial page, the Pearson logo, and the cover of the Pearson book, 5th Edition.
• Initial Page address: 128.119.245.12
• Pearson Logo: 165.193.140.14
• Pearson book, 5th Edition: 128.119.240.90

17. Can you tell whether your browser downloaded the two images serially, or whether they were downloaded from the two web sites in parallel? Explain.

• The browser downloaded the two images in serially. I believe this to be the case because the first image was requested and sent before the second image was requested by the browser. Had they been running in parallel, both files would have been requested then would have returned in the same time period. In this case however, the second image was only requested after the first image came back.