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Wireshark Quickstart Guide

Appendix 3: Hits Versus Page Views

It may take more effort than you realize to deliver a web page to

your computer. The first step is to get the raw HTML code for

the page. Getting this code takes several sets of packets – the

details will be left to an exercise to be completed later, but

suffice it to say that retrieval includes setup and control packets

as well as query and response packets. Furthermore, in most

cases the response will be a multi-packet data burst that must be

reassembled into a complete http response.

However, once the page is delivered to the application, the

system has only completed the first step required to display the

web page. Let’s consider a simplified web page in HTML, as

shown in the box below.

<HTML>

<Body>

Look at this pretty Christmas tree.<br>

</Body>

</HTML>

Figure 12: Simplified Web Page

This web page will display a short sentence (Look at this pretty

Christmas tree.), followed by a line break, and then a picture of

a tree. Notice that the picture of the tree is not part of the HTML

page that is delivered. All that gets delivered with the page is a

placeholder that tells the browser to get the picture called

tree.jpg and to put it into a specific spot on the page.

So, once the browser deciphers the web page, it knows it must

make another request of the web server. Now the browser asks

for the picture tree.jpg. As a result, displaying this page takes

two hits on the browser. One hit (or request) was for the original

web page, and the second hit was for the picture to be

embedded into the web page. Each additional picture or external

page element is another hit on the web page.

How many pictures are on a single page? 10? 20? A recent

analysis of the CNN front page indicated over one hundred and

fifty separate files were required to display the page. A lot of

these files are graphic files. This includes tiny graphic arrows,

almost invisible lines, menu choices, and advertisements. In

addition, javascript files, stylesheets, and iFrames can all be

external links, and thus can be additional sources of hits.

This topic is

appropriate for this

guide because it helps

explains the plethora

of packets that add

together to display a

single web page.

However, it is also

interesting to consider

the implications for

the number of ‘hits’ a

web site gets.

Let’s analyze what it

takes to get a million

hits on a web page.

First, assume an

average page has 150

images. In

comparison, this

would be 10% smaller

than CNN’s front

page. Now, assume

each visitor sees three

pages on the web site.

It will take less than

2,300 visitors to get

one million hits on this

hypothetical web site.

150 Hits/Page

X 3 Pages/Visitor

X 2,300 Visitors

= 1,035,000 hits

1 2 ... 17 18 19 20 21 22 23

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