Cloaking - To Cloak or Not to Cloak.
By Sumantra Roy
Page cloaking can broadly be defined
technique used to deliver different web pages under different
circumstances. There are two primary reasons that people use page
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.
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
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
cloaking script can detect whether a search engine or a human being is
visiting a site:
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
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.
and more complicated way is to use I.P. (Internet Protocol) based
This involves the use of an I.P. database which contains a list of the
addresses of all known search engine spiders. When a visitor (a search
or a human) requests a page, the cloaking script checks the I.P.
of the visitor. If the I.P. address is present in the I.P. database,
cloaking script knows that the visitor is a search engine and delivers
page optimized for that search engine. If the I.P. address is not
in the I.P. database, the cloaking script assumes that a human has
the page, and delivers the page which is meant for human visitors.
Although more complicated than
I.P. based cloaking is more reliable and safe because it is very
to fake I.P. addresses.
Now that you have an idea of what
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
to spider the same page that their visitors are going to see. And if
search engines are prevented from doing so, they cannot be confident of
relevant results to their users. In the past, many people have created
pages for some highly popular keywords and then used page cloaking to
people to their real sites which had nothing to do with those keywords.
the search engines allowed this to happen, they would suffer because
users would abandon them and go to another search engine which produced
Of course, a question arises as to
can detect whether or not a site uses page cloaking. There are three
by which it can do so:
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.
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.
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
advice is simple: don't even think about using it.
Article by Sumantra Roy. Sumantra is
respected search engine positioning specialists on the Internet. To
Sumantra's company place your site at the top of the search engines, go
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