Page
Cloaking - To Cloak or Not to Cloak.
By Sumantra Roy
Page cloaking can broadly be defined as a
technique used to deliver different web pages under different circumstances. There are two
primary reasons that people use page cloaking:
i) It allows them to create a separate
optimized page for each search engine and another page which is aesthetically pleasing and
designed for their human visitors. When a search engine spider visits a site, the page
which has been optimized for that search engine is delivered to it. When a human visits a
site, the page which was designed for the human visitors is shown. The primary benefit of
doing this is that the human visitors don't need to be shown the pages which have been
optimized for the search engines, because the pages which are meant for the search engines
may not be aesthetically pleasing, and may contain an over-repetition of keywords.
ii) It allows them to hide the source code of
the optimized pages that they have created, and hence prevents their competitors from
being able to copy the source code.
Page cloaking is implemented by using some
specialized cloaking scripts. A cloaking script is installed on the server, which detects
whether it is a search engine or a human being that is requesting a page. If a search
engine is requesting a page, the cloaking script delivers the page which has been
optimized for that search engine. If a human being is requesting the page, the cloaking
script delivers the page which has been designed for humans.
There are two primary ways by which the
cloaking script can detect whether a search engine or a human being is visiting a site:
i) The first and simplest way is by checking
the User-Agent variable. Each time anyone (be it a search engine spider or a browser being
operated by a human) requests a page from a site, it reports an User-Agent name to the
site. Generally, if a search engine spider requests a page, the User-Agent variable
contains the name of the search engine. Hence, if the cloaking script detects that the
User-Agent variable contains a name of a search engine, it delivers the page which has
been optimized for that search engine. If the cloaking script does not detect the name of
a search engine in the User-Agent variable, it assumes that the request has been made by a
human being and delivers the page which was designed for human beings.
However, while this is the simplest way to
implement a cloaking script, it is also the least safe. It is pretty easy to fake the
User-Agent variable, and hence, someone who wants to see the optimized pages that are
being delivered to different search engines can easily do so.
ii) The second and more complicated way is to
use I.P. (Internet Protocol) based cloaking. This involves the use of an I.P. database
which contains a list of the I.P. addresses of all known search engine spiders. When a
visitor (a search engine or a human) requests a page, the cloaking script checks the I.P.
address of the visitor. If the I.P. address is present in the I.P. database, the cloaking
script knows that the visitor is a search engine and delivers the page optimized for that
search engine. If the I.P. address is not present in the I.P. database, the cloaking
script assumes that a human has requested the page, and delivers the page which is meant
for human visitors.
Although more complicated than User-Agent
based cloaking, I.P. based cloaking is more reliable and safe because it is very difficult
to fake I.P. addresses.
Now that you have an idea of what cloaking is
all about and how it is implemented, the question arises as to whether you should use page
cloaking. The one word answer is "NO". The reason is simple: the search engines
don't like it, and will probably ban your site from their index if they find out that your
site uses cloaking. The reason that the search engines don't like page cloaking is that it
prevents them from being able to spider the same page that their visitors are going to
see. And if the search engines are prevented from doing so, they cannot be confident of
delivering relevant results to their users. In the past, many people have created
optimized pages for some highly popular keywords and then used page cloaking to take
people to their real sites which had nothing to do with those keywords. If the search
engines allowed this to happen, they would suffer because their users would abandon them
and go to another search engine which produced more relevant results.
Of course, a question arises as to how a
search engine can detect whether or not a site uses page cloaking. There are three ways by
which it can do so:
i) If the site uses User-Agent cloaking, the
search engines can simply send a spider to a site which does not report the name of the
search engine in the User-Agent variable. If the search engine sees that the page
delivered to this spider is different from the page which is delivered to a spider which
reports the name of the search engine in the User-Agent variable, it knows that the site
has used page cloaking.
ii) If the site uses I.P. based cloaking, the
search engines can send a spider from a different I.P. address than any I.P. address which
it has used previously. Since this is a new I.P. address, the I.P. database that is used
for cloaking will not contain this address. If the search engine detects that the page
delivered to the spider with the new I.P. address is different from the page that is
delivered to a spider with a known I.P. address, it knows that the site has used page
cloaking.
iii) A human representative from a search
engine may visit a site to see whether it uses cloaking. If she sees that the page which
is delivered to her is different from the one being delivered to the search engine spider,
she knows that the site uses cloaking.
Hence, when it comes to page cloaking, my
advice is simple: don't even think about using it.
Article by Sumantra Roy. Sumantra
is one of the most respected search engine positioning specialists
on the Internet. To have Sumantra's company place your site
at the top of the search engines, go to http://www.1stSearchRanking.com
For more advice on how you can take your web site to the top
of the search engines, subscribe to his FREE newsletter by going
to http://www.1stSearchRanking.com/wsletter.htm
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